A method for manufacturing an integrated flexible solid-state battery having both ion and electron conduction channels

Abstract

The application relates to a preparation method of an integrated flexible solid-state battery with ion and electron double-conducting channels. By combining atomized active particles with carbon nanotube macro-tubular continuum, a flexible thin film electrode is formed through layer-by-layer assembly and is used as an electron three-dimensional framework, and then a solid-state polymer electrolyte is fully combined into the electrode in a permeation and in-situ polymerization mode. Without adding additional binders and conductive agents, the complicated solid-solid interface in the solid-state battery electrode is simplified, the three-dimensional carbon nanotube network framework enables the electrode to have certain mechanical strength and continuous electron conduction path, and the in-situ polymerization of the high ionic conductive electrolyte also solves the ion conduction problem. The novel composite electrode has good interface contact, simple and stable interface structure and continuous charge conduction channel. The application can make the solid-state battery have higher rate performance, high safety, high energy density and flexibility, and the production method is simple and fast, and has the prospect of commercial scale application.

Description

Technical Field

[0001] The present invention relates to a method for preparing a flexible solid-state battery, and in particular to a method for preparing a flexible solid-state battery with dual conductive channels of ions and electrons. Background Art

[0002] With the rapid development of the flexible electronics industry, flexible electronic devices such as wearable devices, skin sensors, bendable smart cards, and flexible displays are emerging in an endless stream. Batteries in flexible electronic devices are subject to frequent mechanical deformations, such as bending, folding, and twisting, which also poses safety risks. However, most current batteries use liquid electrolytes, which cannot meet the flexibility and safety requirements of wearable devices. To keep pace with the rapid development of flexible electronics, solid-state electrolytes have attracted widespread attention. Compared with traditional electrolytes, solid-state electrolytes are less volatile and have higher thermal stability and safety. Some solid-state electrolytes also exhibit high electrochemical stability at high voltages, making them suitable for high-voltage cathodes and significantly increasing energy density. However, current solid-state batteries face interface issues between the electrolyte and electrode materials, as well as electrolyte electrochemical performance issues, which limit their application in flexible batteries. Furthermore, traditional electrode materials have complex solid-solid interfaces. The addition of binders and conductive agents disrupts ionic and electronic conduction within the electrode, increasing interfacial impedance, polarization, and significant battery capacity degradation. This makes solid-state electrolyte systems unsuitable, especially for flexible solid-state batteries. To optimize the interfacial contact within solid-state battery electrodes and improve charge transfer efficiency within the electrodes, scientists have conducted extensive research, primarily focusing on increasing the contact between solid-state electrolytes and active materials. For example, Archer et al., in their article "Solid-state polymer electrolytes with in-built fast interfacial transport for secondary lithium batteries," published in Nature Energy, Vol. 4, 2019, pp. 365-373, proposed that aluminum cations can trigger the ring-opening polymerization of molecular ethers to produce solid polymer electrolytes. Adding aluminum trifluoromethanesulfonate (Al(OTf)3) to a poly(1,3-dioxolane) (DOL) electrolyte can form an in-situ solid electrolyte (PDOL) within the battery, maintaining conformal interfacial contact with all battery components and reducing the interfacial impedance between the electrodes and the electrolyte. Yang et al. proposed in the article "High-areal-capacity all-solid-state lithium batteries enabled by rational design of fastion transport channels in vertically-aligned composite polymer electrodes" in "Nano Energy" Vol. 61, pp. 567-575, 2019, that a glass fiber reinforced composite polymer electrolyte based on polyethylene oxide (PEO@GF) is combined with a freeze-cast vertically aligned (VL) electrode to promote Li +Transport in highly loaded electrodes. A 10.5 mg cm -2 The high-load battery can provide 1.52 mAh cm -2 High areal capacity. In "Electrolytemelt infiltration for scalable manufacturing of inorganic all-solid-state lithium-ion batteries," published in Nature Materials, Vol. 20, 2021, pp. 984-990, Yushin et al. proposed infiltrating a low-melting-point solid electrolyte into a dense electrode in liquid form at a moderately elevated temperature (~300°C or above) and then solidifying during cooling, thereby achieving closer contact between the solid electrolyte and the active material and increasing the contact area. However, these studies have only considered ion transport within the electrode, ignoring electron transport. The addition of a solid electrolyte also has a certain impact on the movement of electrons within the electrode. The lack of fast electron transport channels in the composite electrode leads to an increase in the battery overpotential and a decrease in rate performance. Solid electrolytes have unique ion transport properties, making it difficult to perfectly integrate them with traditional electrode electronic structures. Therefore, redesigning the electrode structure to construct an electrode structure suitable for solid-state electrodes and rationally adjusting the distribution of electron and ion transport channels can fundamentally solve the charge transport problem within the active material within the electrode. Summary of the Invention

[0003] The purpose of the present invention is to address the above problems and provide a method for preparing an integrated flexible solid-state battery with dual conductive channels for ions and electrons, by combining atomized active particles with a macroscopic tubular continuum of carbon nanotubes and assembling them layer by layer to form a flexible thin film electrode, and then fully integrating the solid polymer electrolyte into the interior of the electrode by means of infiltration and in situ polymerization, without the need to add additional binders and conductive agents. The surface functional groups of the three-dimensional carbon nanotube network framework are combined with the active substances, so that the electrode has a certain mechanical strength and a continuous electron conduction path. The in situ polymerization of the high ionic conductivity electrolyte also solves the ion conduction problem. The composite electrode has good interface contact, a simple and stable interface structure, and a continuous charge conduction channel. The electrode prepared with it can make the solid-state battery have higher rate performance, high safety, high energy density and flexibility, and has the prospect of commercial-scale application.

[0004] The purpose of the invention is achieved through the following technical solution. The present invention relates to a method for preparing an integrated flexible solid-state battery with dual ion and electron conductive channels. The carbon nanotube / solid electrolyte composite electrode involved in the present invention has good flexibility and fast and continuous electron and ion transmission channels. The solid-state battery prepared therefrom has excellent rate performance, high safety, high energy density, and flexibility. The method comprises the following steps:

[0005] Step 1: Construction of a three-dimensional electronic conductive network of carbon nanotubes: Using the method for preparing a composite electrode, the selection of positive electrode active material includes but is not limited to lithium cobalt oxide (LCO), lithium iron phosphate (LFP), lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium nickel cobalt aluminum oxide; the selection of negative electrode active material includes but is not limited to lithium titanate (LTO), carbon negative electrode materials, oxide materials, alloy negative electrode materials, tin-based negative electrode materials, lithium transition metal nitride negative electrode materials, and nanoscale materials. A certain amount of positive and negative electrode active material is weighed and dispersed in an ethanol solution to prepare a spray solution with a mass concentration of 1-100 g / L. Ultrasonic dispersion is performed for 20-60 minutes and then set aside. The dispersed positive and negative electrode active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes using an electric atomizer and collected with a collection roller. Through layer-by-layer assembly, an electrode coated with active material coated with carbon nanotubes is formed. The active material loading in the electrode is controlled to be 5-20 mg / cm 2 By standing for 1-12 hours or 40-120 o Dry at 400°C for 0.5-4 h to evaporate the ethanol, then remove the electrode from the collection roll. Compact the fluffy electrode using a motorized roller machine (double-roller gap 50-200 μm), then place it in a drying oven for storage.

[0006] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: The solid electrolyte monomers used include but are not limited to 1,3-dioxolane (DOL), polyethylene glycol dimethyl ether (PEGDMA), and polymethyl methacrylate; initiators include but are not limited to Al(OTf)3 and 2-methylpropionitrile (AIBN); plasticizers include but are not limited to ethylene carbonate (EC), diethyl carbonate (DEC), fluoroethylene carbonate, and hexamethylene diisocyanate; and lithium salts include but are not limited to lithium bistrifluoromethanesulfonyl imide (LiTFSI), lithium hexafluorophosphate, lithium bisoxalatoborate, lithium difluorooxalatoborate, lithium bisdifluorosulfonyl imide, lithium perchlorate, and lithium hexafluoroarsenate. A certain amount of initiator powder is added to a mixed solvent of plasticizers and mixed evenly to obtain a catalyst solution with a mass concentration of 0.5-80 g / L. A certain amount of lithium salt is added to the monomer solvent to prepare a precursor electrolyte with a concentration of 0.5-3 M. Finally, the prepared catalyst solution and precursor electrolyte were uniformly mixed in a volume ratio of 1:20 to 1:2. The mixed solution was then added dropwise to the prepared electrode. After standing for 0.5-4 hours, in-situ polymerization occurred within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H2O ≤ 0.1 ppm; O2 ≤ 0.1 ppm).

[0007] Step 3: Electrode Piece Preparation: For button electrode preparation, use a punching machine to punch the composite electrode polymerized in Step 2 into circular pieces with a diameter of 12-16 mm for the positive electrode piece; 14-28 mm for the negative electrode piece; and 16-20 mm for the separator piece. For soft-pack battery electrode preparation, use a knife and ruler to cut the positive composite electrode into pieces of 50-150 mm x 40-100 mm, leaving 6-10 mm for the welding tabs. Cut the negative composite electrode into pieces of 60-160 mm x 50-110 mm, leaving 6-10 mm for the welding tabs. After preparation, place the prepared electrode pieces in a 60°C vacuum drying oven and dry them for 4-8 hours before use. After use, return them to the drying oven for storage.

[0008] Step 4, battery assembly and liquid injection: Use the dried electrode sheet as the working electrode (positive electrode) of the button battery, and use the purchased lithium sheet as the reference electrode (negative electrode). When assembling, first place the negative electrode shell on the platform, and then put in the negative electrode sheet, diaphragm, positive electrode sheet, electrolyte, gasket, and shrapnel in turn, and finally cover with the positive electrode shell. Use a button battery packaging machine to package it, and the button half-cell assembly is completed. All assembly processes are carried out in a glove box in an argon atmosphere (H2O≤0.1 ppm; O2≤0.1 ppm). The electrode uses the composite electrode polymerized in step 2. The assembly process of single-layer soft-pack batteries is similar to that of button half-cells. The pre-cut (50-80) mm × (40-70) mm electrode is used as the positive electrode, and the negative electrode uses a (60-90) mm × (50-80) mm composite electrode and purchased lithium foil. The size of the middle separator is (70-100) mm × (60-90) mm. Before assembly, the pole tabs are welded to the reserved position of the electrode. After assembly, they are packaged with plastic bags. Lithium foil is used as the negative electrode and packaged with aluminum-plastic film. Multi-layer large-capacity soft-pack batteries are assembled in a stacked manner using composite positive electrode sheets with specifications of (130-160) mm × (80-110) mm and composite negative electrode sheets with specifications of (140-170) mm × (90-120) mm. During assembly, the reserved tabs are placed on both sides of the diaphragm, and the size of the diaphragm is (150-180) mm × (100-130) mm. After assembly, all positive and negative electrode tabs are welded together and finally encapsulated with plastic (PE) film.

[0009] Step 5: Test the performance of the battery prepared above in an electrochemical test cabinet. The composite electrode prepared according to the above steps shows a 3-4.5Ω sq -1 Low sheet resistance and above 10 -11 cm -2 s -1 The lithium ion diffusion coefficient is low and the battery has excellent electronic and ionic conductivity. The half-cell prepared according to the above steps has a capacity of 143.0-165 mAh g -1 High discharge capacity, it can still work normally at a high rate of 8-10 C and has a capacity of 130-100 mAh g -1 The discharge capacity of the electrode is 15-19.4 mg cm -2 In the case of electrode active materials, it can still maintain excellent flexibility, and the assembled half-cell has stable cycle performance, with a coulombic efficiency of 99.8-99.9% and a capacity of 2.5-3 mAh·cm -2 Capacity and 267-320 Wh Kg -1High energy density. The fabricated flexible battery retains 97%-89% of its capacity after 500-2000 bends. The lithium-ion battery does not catch fire during scissor cutting and maintains stable voltage and current output. Lithium metal soft-pack batteries assembled with composite electrodes continue to operate stably for 3-5 hours after cutting and needle penetration tests.

[0010] Specifically, a composite electrode is prepared by coating active materials with a macroscopic tubular continuum of carbon nanotubes, and using it as an electronic three-dimensional framework to in-situ polymerize solid electrolytes inside to construct a dual-charge rapid transmission channel, reduce the interface impedance within the solid-state battery, and improve the charge transfer efficiency, thereby preparing an integrated solid-state battery with high rate performance, safety performance and energy density.

[0011] The present invention has the following beneficial effects: the interior of the traditional powder electrode is made of a mixed slurry of three substances: active particles, binder and conductive agent. When a solid electrolyte is introduced, the internal interface of the electrode is complex, which greatly affects the transfer of charge in the electrode. The complex interface may also lead to side reactions. In the absence of continuous and stable interface contact, the conduction path of ions in the electrode will also be more tortuous, and the ion transfer rate will decrease. When solid electrolytes are used in flexible and wearable electronic devices, the traditional powder electrode active material layer is not tightly bonded to the current collector, and the active material will fall off after several bends. In particular, the contact area between the active particles and the solid electrolyte in the electrode is small, the ion transport is slow, and the interface resistance is large, which greatly reduces the performance of the flexible solid-state battery. The present invention is a technology for preparing a composite electrode by coating the active material with a macroscopic tubular continuum of carbon nanotubes, and using it as an electronic three-dimensional framework to in-situ polymerize the solid electrolyte inside to construct a dual-charge rapid transfer channel, reduce the interface impedance in the solid-state battery and improve the charge transfer efficiency, and prepare an integrated solid-state battery with high rate performance, safety performance and energy density. The improvements made by the present invention offer the following advantages. First, the present invention proposes a simple method for constructing a polymerized, integrated solid-state lithium battery with interconnected conductive interfaces. The surface functional groups of the macroscopic tubular continuum of carbon nanotubes can densely bind to the active material. The voids therein are filled with a liquid solid electrolyte precursor and then polymerized. The resulting double-layer coating of carbon nanotubes and solid electrolyte creates charge transfer channels between the active particles, allowing rapid electron and ion conduction between the active particles, significantly reducing interfacial internal resistance, thereby improving electron and ion transfer efficiency and enhancing electrochemical reaction kinetics. Second, the prepared integrated lithium battery with a solid electrolyte and fewer phases can be used to address poor interfacial contact and discrete interfacial transport throughout the electrode. Without the addition of any conductive material or binder, the active material electrode is fixed to the self-supporting carbon nanotubes by wetting them with a low-viscosity precursor electrolyte. Therefore, the in-situ polymerized carbon nanotubes and solid electrolyte can tightly integrate the positive and negative electrodes into the battery. Third, the oxygen in the electrolyte precursor and initiator can capture lithium from the active material, while the carbon nanofilm has a high absorption capacity. Therefore, there is good interface contact between the solid electrolyte and the active material, a tight electrode structure, and a continuous and fast charge transfer channel; Fourth, the preparation of an integrated solid-state lithium battery achieves good flexibility, low resistance, high lithium ion diffusion efficiency, high energy density, high capacity retention and excellent cycle life. The lithium metal soft-pack battery assembled with the composite electrode can still work stably after cutting and needle puncture tests. After the integrated flexible solid-state battery uses plastic film instead of the traditional aluminum-plastic film packaging, it can still maintain good cycle stability, has excellent environmental applicability and high safety, and the exposed battery can still work normally when bent and cut.The resulting large-capacity flexible solid-state battery maintains excellent bendability and stable electrochemical performance. When sewn onto clothing, it naturally flexes with the garment, making it highly wearable. Therefore, this invention successfully achieves an integrated lithium battery with excellent electrochemical kinetics, complete flexibility, and sufficient safety. This work provides a new approach to the development of safe solid-state batteries. DETAILED DESCRIPTION

[0012] The following is a detailed description of an embodiment of the present invention: This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0013] Example 1.

[0014] Step 1: Construction of a three-dimensional electronic conductive network of continuous carbon nanotubes: LFP is selected as the positive electrode active material. A certain amount of LFP is weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 30 g / L. The ultrasonic power is 400W and ultrasonic dispersion is carried out for 30 minutes before use. The dispersed positive and negative active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes through an electric atomizer and collected with a collection roller. Through layer-by-layer assembly, an electrode coated with carbon nanotubes and active materials (CNTs@LFP) is formed. The active material loading in the electrode is controlled to 5 mg / cm 2 .50 o After drying at 400 °C for 2 h to evaporate the ethanol, the electrodes were peeled off the collecting roller. The fluffy electrodes were compacted using a motorized roller mill (with a 50 μm gap between the rollers) and then stored in a drying oven.

[0015] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: Al(OTf)₃ powder was added to tetrahydrofuran (THF) solvent and mixed thoroughly to obtain a catalyst solution with a concentration of 18 g / L. A predetermined amount of LiTFSI powder was added to the DOL solvent and stirred to prepare a precursor electrolyte solution with a concentration of 2 M. Finally, the prepared Al(OTf)₃ / THF catalyst solution and the LiTFSI / DOL precursor electrolyte were uniformly mixed in a volume ratio of 1:20. After standing for 2 hours, the mixture polymerized within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0016] Step 3: Prepare the button electrode: Use a punching machine to punch the composite electrode from Step 2 into a circular electrode with a diameter of 14 mm for the positive electrode and 18 mm for the separator. Place the prepared electrode in a 60°C vacuum drying oven for 12 hours before use. Return it to the drying oven for storage after use.

[0017] Step 4, battery assembly and liquid injection: Use the electrode sheet dried in step 3 as the positive electrode of the button battery, and use the purchased lithium sheet as the negative electrode. When assembling, first place the negative electrode shell on the platform, and then put in the negative electrode sheet, diaphragm, positive electrode sheet, electrolyte, gasket, and shrapnel in turn, and finally cover with the positive electrode shell. Use a button battery packaging machine to package it, and the button half-cell assembly is completed. All assembly processes are carried out in a glove box in an argon atmosphere (H2O≤0.1 ppm; O2≤0.1 ppm).

[0018] In this example, an impedance spectroscopy (EIS) test was performed on the battery. The EIS starting point of the CNTs@LFP half-cell was 3Ω, which is lower than the 4.9Ω of a conventional lithium iron phosphate powder (Al@LFP) half-cell. The charge transfer resistance of the CNTs@LFP half-cell was approximately 27Ω, while that of the Al@LFP half-cell was approximately 434Ω, 16 times that of the CNTs@LFP half-cell. After 200 charge and discharge cycles, the charge transfer resistance of the CNTs@LFP half-cell remained stable at approximately 25Ω, while that of the Al@LFP half-cell increased to 1935Ω. The fabricated battery was cycled at a rate of 10C between 2.5 and 3.85 V. The charge and discharge curves of the battery showed no significant change with increasing cycle number, and the charge and discharge polarization voltages and discharge capacity remained stable, demonstrating good electrochemical reversibility. The rate tests were carried out at 0.5 C, 1 C, 2 C, 3 C, 5 C, and 10 C. At the rate of 0.5 C, the discharge capacity of the CNTs@LFP half-cell was 145.7 mAh g -1 , while the discharge capacity of Al@LFP half-cell is only 126 mAh g -1 With the increase of current density, the CNTs@LFP half-cell can still maintain a high charge and discharge capacity, with a capacity of 124.7 mAh g at a rate of 5 C. -1 The discharge capacity of the Al@LFP half-cell is only 76.8 mAh g at 5C. -1 When the rate increases to 10 C, the discharge capacity decreases to almost 0 mAh g -1 .

[0019] Example 2.

[0020] Step 1: Construction of a three-dimensional electronic conductive network of continuous carbon nanotubes: LCO is selected as the positive electrode active material. A certain amount of LCO is weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 25 g / L. The ultrasonic power is 500 W and ultrasonic dispersion is carried out for 40 minutes before use. The dispersed positive and negative active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes using an electric atomizer and collected with a collection roller. Through layer-by-layer assembly, an electrode coated with active materials by carbon nanotubes (CNTs@LCO) is formed. The active material loading in the electrode is controlled to 10 mg / cm 2 After standing for 6 hours to allow the ethanol to evaporate, the electrodes were removed from the collection roller. The fluffy electrodes were compacted using a motorized roller mill (with a 70 μm gap between the rollers) and then stored in a drying oven.

[0021] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: Al(OTf)₃ powder was added to THF solvent and mixed thoroughly to obtain a catalyst solution with a concentration of 15 g / L. A predetermined amount of LiTFSI powder was then added to DOL solvent and stirred thoroughly to prepare a precursor electrolyte solution with a concentration of 2 M. Finally, the prepared Al(OTf)₃ / THF catalyst solution and LiTFSI / DOL precursor electrolyte were uniformly mixed in a volume ratio of 1:10. After standing for 1 hour, the electrolyte polymerized within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0022] Step 3: Preparation of button electrode plates: Use a plate punching machine to punch the composite electrode prepared in step 2 into a circular plate with a diameter of 12 mm; punch the diaphragm into a circular plate with a diameter of 16.7 mm; after the plate is prepared, place it in a 60°C vacuum drying oven and dry it for 10 hours before use. After use, put it back into the drying oven for storage.

[0023] Step 4, battery assembly and liquid injection: Use the composite electrode sheet dried in step 3 as the positive electrode of the button battery, and use the purchased lithium sheet as the negative electrode. When assembling, first place the negative electrode shell on the platform, and then put in the negative electrode sheet, diaphragm, positive electrode sheet, electrolyte, gasket, and shrapnel in turn, and finally cover with the positive electrode shell. Use a button battery packaging machine to package, and the button half-cell assembly is completed. All assembly processes are carried out in a glove box in an argon atmosphere (H2O≤0.1 ppm; O2≤0.1 ppm).

[0024] In this embodiment, an EIS test was performed on the above-mentioned battery. The EIS starting point of the CNTs@LCO half-cell was 2.6 Ω, which was less than the 4.3 Ω of the traditional lithium titanate powder (Al@LCO) half-cell. The charge transfer resistance of the CNTs@LCO half-cell was about 17 Ω, while the charge transfer resistance of the Al@LCO half-cell was about 435 Ω, which was 26 times that of the CNTs@LCO half-cell. After 200 charge and discharge cycles, the charge transfer resistance of the CNTs@LCO half-cell remained unchanged at about 19 Ω, while the charge transfer resistance of the Al@LCO half-cell increased to 1691 Ω. The prepared battery was tested at 0.5C, 1C, 2C, 3C, 5C, and 10C rates. At a rate of 0.5C, the discharge capacity of the CNTs@LCO half-cell was 139 mAh g -1 , while the discharge capacity of Al@LCO half-cell is only 118 mAh g -1 With the increase of current density, the CNTs@LCO half-cell can still maintain a high charge and discharge capacity, with a capacity of 112.9 mAh g at a rate of 5 C. -1 The discharge capacity of the Al@LCO half-cell is only 79.4 mAh g at 5C. -1 When the rate increases to 10 C, the discharge capacity decreases to almost 0 mAh g -1 .

[0025] Example 3.

[0026] Step 1: Construction of a three-dimensional electronic conductive network of continuous carbon nanotubes: LCO was selected as the positive electrode active material. A certain amount of LCO was weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 45 g / L. Ultrasonic power was 600 W and ultrasonic dispersion was carried out for 60 minutes before use. The dispersed positive and negative active materials were sprayed onto the macroscopic tubular continuum of carbon nanotubes using an electric atomizer and collected with a collection roller. The composite electrode CNTs@LFP was formed by layer-by-layer assembly. The active material loading in the electrode was controlled to 15 mg / cm 2 . Pass 70 oThe electrodes were dried at 400 °C for 3 h to evaporate the ethanol, and then peeled off the collecting roller. The fluffy electrodes were compacted using an electric roller mill (100 μm gap between the rollers) and stored in a drying oven. Graphite (GRA) was selected as the negative electrode active material. A certain amount of GRA was weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 45 g / L. Ultrasonic dispersion was performed at 600 W for 90 min and then set aside. The dispersed positive and negative active materials were sprayed onto the carbon nanotube film using an electric atomizer and collected using a collecting roller to form a carbon nanotube-coated active material electrode (CNTs@GRA). The active material loading in the electrode was controlled to 13 mg / cm. 2 . Pass 70 o After drying at 4°C for 4 h to evaporate the ethanol, the electrodes were peeled off the collecting roller. The fluffy electrodes were compacted using a motorized roller machine (100 μm gap between the rollers) and then stored in a drying oven.

[0027] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: Al(OTf)₃ powder was added to THF solvent and mixed thoroughly to obtain a catalyst solution with a concentration of 50 g / L. A certain amount of LiTFSI powder was then added to DOL solvent and stirred thoroughly to prepare a precursor electrolyte solution with a concentration of 1.5 M. Finally, the prepared Al(OTf)₃ / THF catalyst solution and LiTFSI / DOL precursor electrolyte were uniformly mixed in a volume ratio of 1:12. After standing for 1 hour, the electrolyte polymerized within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0028] Step 3, preparation of soft-pack battery pole pieces: Use a knife and a ruler to cut the composite positive electrode prepared in step 2 into a size of 50 mm × 40 mm, leaving 10 mm for the welding tab position, and the actual effective area is 40 mm × 40 mm; cut the composite negative electrode prepared in step 2 into a size of 60 mm × 50 mm, leaving 10 mm for the welding tab position, and the actual effective area is 50 mm × 50 mm; after the pole piece is prepared, put it in a 60 ° C vacuum drying oven, dry it for 12 hours and it can be used. After use, put it back into the drying oven for storage.

[0029] Step 4: Battery Assembly and Fluid Filling: Use the 50 mm × 40 mm electrode sheet cut and dried in Step 3 as the positive electrode, and the 60 mm × 50 mm electrode sheet from Step 3 as the negative electrode. The intermediate separator measures 70 mm × 60 mm. Before assembly, weld the tabs to the reserved spaces on the electrode sheets. After assembly, seal with PE film. All assembly processes are performed in a glove box with an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0030] In this embodiment, the prepared battery was cycled at a rate of 0.5 C between 3 and 4.2 V, and the coulombic efficiency remained above 99% during the cycle. The large-capacity flexible solid-state battery has a smooth and long charge and discharge platform, a charge and discharge polarization voltage of 96.3 mV, and a discharge capacity of up to 288 mAh g -1 After 100 cycles, the capacity retention rate was 95.7%, higher than the 72.3% of traditional powder batteries. The prepared battery retained 94.2% of its capacity after 600 bends. The lithium-ion battery did not catch fire during the scissor cutting process and was able to maintain stable voltage and current output.

[0031] Example 4.

[0032] Step 1: Construction of a three-dimensional electronic conductive network of continuous carbon nanotubes: LFP is selected as the positive electrode active material. A certain amount of LFP is weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 65 g / L. The ultrasonic power is 550 W and ultrasonic dispersion is carried out for 40 minutes before use. The dispersed positive and negative active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes through an electric atomizer and collected with a collection roller. The composite electrode CNTs@LFP is formed by layer-by-layer assembly. The active material loading in the electrode is controlled to 15 mg / cm 2 . After standing for 6 hours to allow the ethanol to evaporate, peel it off the collecting roller. Use an electric roller machine (double roller spacing 80 μm) to compact the fluffy electrode, and place it in a drying oven for storage after rolling; LTO is selected as the negative electrode material. Weigh a certain amount of LTO and disperse it in an ethanol solution to prepare a spray solution with a concentration of 40g / L. The ultrasonic power is 550W, and the ultrasonic dispersion is carried out for 50 minutes before use; the dispersed positive and negative active materials are sprayed on the carbon nanotube film through an electric atomizer and collected with a collecting roller to form a composite electrode CNTs@LTO. The active material loading in the electrode is controlled at 18mg / cm 2 After standing for 8 hours to allow the ethanol to evaporate, the electrodes were removed from the collection roller. The fluffy electrodes were compacted using a motorized roller mill (80 μm gap between the rollers) and then stored in a drying oven.

[0033] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: Al(OTf)₃ powder was added to THF solvent and mixed thoroughly to obtain a catalyst solution with a concentration of 28 g / L. A predetermined amount of LiTFSI powder was then added to DOL solvent and stirred thoroughly to prepare a precursor electrolyte solution with a concentration of 2M. Finally, the prepared Al(OTf)₃ / THF catalyst solution and LiTFSI / DOL precursor electrolyte were uniformly mixed in a volume ratio of 1:5. After standing for 1 hour, the mixture polymerized within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0034] Step 3, preparation of soft-pack battery electrodes: Use a knife and a ruler to cut the composite positive electrode electrode polymerized in step 2 into a size of 150 mm × 100 mm, leaving 8 mm for the welding tab position, and the actual effective area is 142 mm × 100 mm; cut the composite negative electrode polymerized in step 2 into a size of 160 mm × 110 mm, leaving 18 mm for the welding tab position, and the actual effective area is 152 mm × 110 mm; after the electrode is prepared, place it in a 60 ° C vacuum drying oven and dry it for 12 hours before use. After use, put it back into the drying oven for storage.

[0035] Step 4: Battery Assembly and Fluid Filling: The 150 mm × 100 mm composite electrode sheet cut and dried in Step 3 is used as the positive electrode, and a 160 mm × 110 mm composite electrode sheet is used for the negative electrode. The intermediate separator measures 170 mm × 120 mm. Before assembly, the tabs are welded to the reserved positions on the electrode sheets. After assembly, the battery is finally encapsulated with PE film. All assembly processes are performed in a glove box with an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0036] In this embodiment, the prepared battery was cycled at a rate of 0.5 C between 1.0 and 2.5 V, and the discharge capacity hardly decayed with each cycle. The large-capacity flexible solid-state battery has a smooth and long charge and discharge platform, a charge and discharge polarization voltage of 93 mV, and a discharge capacity of up to 249.6 mAh g -1 After 150 cycles, the capacity retention rate was 95.3%, compared to 69.7% for conventional powder batteries. The prepared battery retained 94.2% of its capacity after 700 bends. The lithium-ion battery did not catch fire during the scissor cutting process and maintained stable voltage and current output.

[0037] Example 5.

[0038] Step 1: Construction of a three-dimensional electronic conductive network of continuous carbon nanotubes: LCO is selected as the positive electrode active material. A certain amount of LCO is weighed and dispersed in an ethanol solution to prepare a spray solution with a concentration of 80 g / L. The ultrasonic power is 600 W and ultrasonic dispersion is carried out for 50 minutes before use. The dispersed positive and negative active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes using an electric atomizer and collected with a collection roller. The composite electrode CNTs@LCO is formed by layer-by-layer assembly. The active material loading in the electrode is controlled to 20 mg / cm 2 . Pass 60 o After drying at 400 °C for 1.5 h to evaporate the ethanol, the electrode was peeled off the collecting roller. The fluffy electrode was compacted using a motorized roller machine (100 μm gap between the rollers) and then stored in a drying oven.

[0039] Step 2: In-situ polymerization of the solid electrolyte within the flexible electrode: AIBN powder was added to a 1:1 volume ratio of EC and DEC to obtain an initiator solution with a concentration of 30 g / L. The precursor electrolyte was then prepared by adding 0.8 g of LiTFSI powder to 2 g of PEGDMA as a monomer solvent. The prepared initiator solution and monomer electrolyte were then uniformly mixed in a volume ratio of 1:7. The mixed solution was then dropwise added to the prepared electrode. After standing for 1.5 hours, in-situ polymerization occurred within the electrode to form an integrated composite electrode. All preparation processes were performed in a glove box under an argon atmosphere (H₂O ≤ 0.1 ppm; O₂ ≤ 0.1 ppm).

[0040] Step 3: Preparation of button electrode plates: Use a plate punching machine to punch the composite electrode prepared in step 2 into a circular plate with a D of 13 mm; punch the diaphragm into a circular plate with a D of 17 mm; after the plate is prepared, place it in a 60 ° C vacuum drying oven and dry it for 12 hours before use. After use, put it back into the drying oven for storage.

[0041] Step 4, battery assembly and liquid injection: Use the composite electrode dried in step 3 as the positive electrode of the button battery, and use the purchased lithium sheet as the negative electrode. When assembling, first place the negative electrode shell on the platform, and then put in the negative electrode sheet, diaphragm, positive electrode sheet, electrolyte, gasket, and shrapnel in turn, and finally cover with the positive electrode shell. Use a button battery packaging machine to package it, and the button half-cell assembly is completed. All assembly processes are carried out in a glove box in an argon atmosphere (H2O≤0.1 ppm; O2≤0.1 ppm).

[0042] In this embodiment, an EIS test was performed on the above-mentioned battery. The EIS starting point of the CNTs@LCO half-cell was 1.9 Ω, which was less than 4.7 Ω of the Al@LCO half-cell. The charge transfer resistance of the CNTs@LCO half-cell was about 13 Ω, while the charge transfer resistance of the Al@LCO half-cell was about 264 Ω, which was 20 times that of the CNTs@LCO half-cell. After 200 cycles of charge and discharge, the charge transfer resistance of the CNTs@LCO half-cell remained unchanged at about 10.4 Ω, while the charge transfer resistance of the Al@LCO half-cell increased to 1491 Ω. The prepared battery was tested at a rate of 0.5 C, 1 C, 2 C, 3 C, 5 C, and 10 C. At a rate of 0.5 C, the discharge capacity of the CNTs@LCO half-cell was 140 mAh g-1, while the discharge capacity of the Al@LCO half-cell was only 123 mAh g-1. -1 With the increase of current density, the CNTs@LCO half-cell can still maintain a high charge and discharge capacity, with a capacity of 119 mAh g at a rate of 5 C. -1 The discharge capacity of the Al@LCO half-cell is only 69.8 mAh g at 5 C. -1 When the rate increases to 10 C, the discharge capacity decreases to almost 0 mAh g -1 .

Claims

1. A method for preparing an integrated flexible solid-state battery with dual ionic and electronic conductive channels, characterized by: The method comprises the following steps in sequence: Step 1: Construction of a three-dimensional electronic conductive network of carbon nanotubes: Using the method for preparing a composite electrode, a certain amount of positive and negative active material is weighed and dispersed in an ethanol solution to prepare a spray solution. Ultrasonic dispersion is performed for 20-60 minutes and then set aside. The dispersed positive and negative active materials are sprayed onto the macroscopic tubular continuum of carbon nanotubes through an electric atomizer and collected with a collection roller. The electrodes are assembled layer by layer to form carbon nanotube-coated active material electrodes. The active material loading in the electrode is controlled to be 5-20 mg / cm 2 ; by standing for 1-12 h or 40-120 o Dry at 400°C for 0.5-4 h to evaporate the ethanol, peel it off the collecting roller, compact the fluffy electrode with an electric roller machine, and store it in a drying oven after rolling. The distance between the two rollers of the electric roller machine is 50-200 μm. Step 2: In-situ polymerization of the solid electrolyte in the flexible electrode: a certain amount of initiator powder is added to a mixed solvent of the plasticizer, and the mixture is evenly mixed to obtain a catalyst solution with a mass concentration of 0.5-80 g / L; a certain amount of lithium salt is added to the solid electrolyte monomer solvent to prepare a precursor electrolyte with a concentration of 0.5-3 M; finally, the prepared catalyst solution and the precursor electrolyte are evenly mixed in a volume ratio of 1:20 to 1:2, and the mixed solution is dropped onto the prepared electrode. After standing for 0.5-4 hours, the mixed solution is in-situ polymerized inside the electrode to form an integrated composite electrode; all preparation processes are carried out in a glove box under an argon atmosphere with H2O ≤ 0.1 ppm; O2 ≤ 0.1 ppm; Step 3, electrode plate preparation: button electrode plate preparation, use a plate punching machine to punch the composite electrode that has been polymerized in step 2, punch the positive electrode plate into a circle with a diameter of 12-16 mm; punch the negative electrode plate into a circular negative electrode plate with a diameter of 14-28 mm; punch the separator into a circular plate with a diameter of 16-20 mm; soft pack battery plate preparation: use a knife and a ruler to cut the positive composite electrode into a size of (50-150) mm × (40-100) mm, leaving 6-10 mm for welding the tab position; cut the negative composite electrode into a size of (60-160) mm × (50-110) mm, leaving 6-10 mm for each welding tab position; after the plate is prepared, put it in a 60 ° C vacuum drying oven, dry it for 4-8 hours before use, and put it back into the drying oven for storage after use; Step 4, battery assembly and injection: Use the dried electrode sheet as the working electrode of the button battery, the positive electrode, and use the purchased lithium sheet as the reference electrode, the negative electrode. When assembling, first place the negative electrode shell on the platform, and then put the negative electrode sheet, diaphragm, positive electrode sheet, electrolyte, gasket, and shrapnel in turn, and finally cover the positive electrode shell. Use the button battery packaging machine to package, and the button half-cell assembly is completed. All assembly processes are carried out in a glove box under argon atmosphere, H2O≤0.1 ppm; O2≤0.1 The electrode is made of the composite electrode prepared in step 2. The assembly process of the single-layer soft-pack battery is similar to that of the button half-cell. The pre-cut (50-80) mm × (40-70) mm electrode is used as the positive electrode, and the negative electrode uses the (60-90) mm × (50-80) mm composite electrode and the purchased lithium foil. The size of the middle separator is (70-100) mm × (60-90) mm. Before assembly, the pole ear is welded to the position reserved for the pole piece. After assembly, it is sealed with a plastic bag. The lithium foil as the negative electrode is packaged with aluminum-plastic film; the multi-layer large-capacity soft-pack battery is assembled with a composite positive electrode sheet with a specification of (130-160) mm × (80-110) mm and a composite negative electrode sheet with a specification of (140-170) mm × (90-120) mm for stacking. During assembly, the reserved tabs are placed on both sides of the diaphragm. The size of the diaphragm is (150-180) mm × (100-130) mm. After the assembly is completed, all the positive and negative tabs are welded together and finally packaged with plastic film.

2. The method for preparing an integrated flexible solid-state battery with dual ionic and electronic conductive channels according to claim 1, characterized in that: The positive electrode active material selected in step 1 includes lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, and lithium nickel cobalt aluminum oxide.

3. The method for preparing an integrated flexible solid-state battery having dual ionic and electronic conductive channels according to claim 1, characterized in that: The negative electrode active material selected in step 1 includes lithium titanate, carbon negative electrode material, oxide material, alloy negative electrode material, and lithium-containing transition metal nitride negative electrode material.

4. The method for preparing an integrated flexible solid-state battery having dual ionic and electronic conductive channels according to claim 1, characterized in that: The mass concentration of the spray solution used in step 1 is 1-100 g / L.

5. The method for preparing an integrated flexible solid-state battery with dual ion and electron conductive channels according to claim 1, characterized in that: The solid electrolyte monomers used in step 2 include 1,3-dioxolane, polyethylene glycol dimethyl ether, and polymethyl methacrylate.

6. The method for preparing an integrated flexible solid-state battery with dual ionic and electronic conductive channels according to claim 1, characterized in that: The initiators used in step 2 include aluminum trifluoromethanesulfonate and 2-methylpropionitrile.

7. The method for preparing an integrated flexible solid-state battery with dual ionic and electronic conductive channels according to claim 1, characterized in that: The plasticizer used in step 2 includes ethylene carbonate, diethyl carbonate, fluoroethylene carbonate, and hexamethylene diisocyanate.

8. The method for preparing an integrated flexible solid-state battery with dual ionic and electronic conductive channels according to claim 1, characterized in that: The lithium salts used in step 2 include lithium bis(trifluoromethanesulfonyl imide), lithium hexafluorophosphate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium bis(difluorosulfonyl imide), lithium perchlorate, and lithium hexafluoroarsenate.