阅读说明：本技术 一种锂离子电池用一体化多孔电极及其制备和应用 (Integrated porous electrode for lithium ion battery and preparation and application thereof ) 是由 张洪章 李先锋 于滢 张华民 于 2019-10-11 设计创作，主要内容包括：本发明公开了一种锂离子电池用一体化多孔电极,将有机高分子树脂分别与电极材料和无机陶瓷电解质混合,依次(先正极浆料,再电解质浆料,最后负极浆料或是先负极浆料,再电解质浆料,最后正极浆料)在基底上刮涂后通过浸没相转化法制备而成正极、隔膜和负极集于一体的一体化多孔电极。与应用于锂离子电池的常规电极相比,一体化多孔电极有较高孔隙率,同时具有贯通的孔结构,有效地加快了电极内部离子传输,提高电池的倍率性能；并且正极、隔膜和负极同时制备且集于一体,简化了电极制备工艺和电池组装工艺,制备方法简单易放大；此外,一体化电极内部高分子树脂连续,极大减少电池内部接触电阻,提高电池的容量,并且有效提高电极粘结性,可用于制备高担载量高能量密度电池；另外,一体化电极使用时无需集流体,在穿戴式和便携式电池方面有广泛的应用前景。(The invention discloses an integrated porous electrode for a lithium ion battery, which is prepared by respectively mixing organic polymer resin with an electrode material and an inorganic ceramic electrolyte, blade-coating the mixture on a substrate in sequence (firstly anode slurry, secondly electrolyte slurry and finally cathode slurry or firstly cathode slurry, secondly electrolyte slurry and finally anode slurry) and then preparing the integrated porous electrode with an integrated anode, a diaphragm and a cathode by an immersion phase conversion method. Compared with the conventional electrode applied to the lithium ion battery, the integrated porous electrode has higher porosity and a through pore structure, effectively accelerates the ion transmission in the electrode and improves the rate capability of the battery; the positive electrode, the diaphragm and the negative electrode are simultaneously prepared and integrated, so that the electrode preparation process and the battery assembly process are simplified, and the preparation method is simple and easy to amplify; in addition, the high polymer resin in the integrated electrode is continuous, so that the internal contact resistance of the battery is greatly reduced, the capacity of the battery is improved, the electrode cohesiveness is effectively improved, and the integrated electrode can be used for preparing a high-load-capacity high-energy-density battery; in addition, the integrated electrode does not need a current collector when in use, and has wide application prospect in the aspects of wearable and portable batteries.)

1. An integrated porous electrode for a lithium ion battery is characterized in that:

mixing an organic polymer resin solution with a positive electrode material, a negative electrode material and an inorganic ceramic electrolyte respectively to form a positive electrode slurry, a negative electrode slurry and an electrolyte slurry respectively; and (2) coating the substrate with positive slurry, electrolyte slurry and negative slurry in sequence, or coating the substrate with negative slurry, electrolyte slurry and positive slurry in sequence, and preparing the integrated porous electrode with the positive electrode, the diaphragm and the negative electrode integrated into a whole by an immersion phase conversion method after coating.

2. The integrated porous electrode of claim 1, wherein:

the organic polymer resin can be one or more of Polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), Polystyrene (PS), polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyvinylidene fluoride (PVDF), polyether sulfone (PES), Polybenzimidazole (PBI) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and the mass content of the organic polymer resin in the organic polymer resin solution is 2-70%;

the positive electrode material is a lithium ion battery positive electrode active material or a mixture of the lithium ion battery positive electrode active material and a conductive carbon material, wherein the conductive carbon material accounts for 0-15% of the mass ratio and can be selected according to the conductivity of the material; the positive active material may be lithium cobaltate (LiCoO)₂) Lithium nickelate (LiNiO)₂) Lithium manganate (Li)_xMn_yO_z) Lithium iron phosphate (LiFePO)₄) And lithium vanadium phosphate (Li)₃V₂(PO4)₃) One or more than two of the above;

the mass ratio of the anode material to the organic polymer resin in the anode can be 1/1-9.5/1;

the negative electrode material is a lithium ion battery negative electrode active material or a mixture of the lithium ion battery negative electrode active material and a conductive carbon material, wherein the conductive carbon material accounts for 0-15% by mass and can be selected according to the conductivity of the material; the negative active material can be one or more than two of graphite, amorphous carbon material, carbon nano tube, graphene, metal oxide and metal sulfide;

the mass ratio of the negative electrode material to the organic polymer resin in the negative electrode can be 1/1-9.5/1;

the conductive carbon material is one or more than two of carbon nano tube, graphene, carbon nano fiber, BP2000, KB600, KB300, XC-72, Super-P, acetylene black and active carbon;

the inorganic ceramic electrolyte can be silicon oxide (SiO)₂) Alumina (A1)₂O₃) Titanium oxide (TiO)₂) And barium titanate (BaTiO)₃) The mass ratio of the inorganic ceramic electrolyte to the organic polymer resin in the electrolyte can be 1/1-3/1.

3. The integrated porous electrode of claim 1, wherein: the substrate may be one of a glass plate, a teflon plate or an aluminum foil.

4. The integrated porous electrode according to any one of claims 1 to 3, wherein: the electrode comprises a positive electrode, an electrolyte diaphragm and a negative electrode, wherein the polymer resin is continuously crosslinked, the pore structure is continuous and through, and the average porosity is 40-65%, preferably 50-60%; the aperture range is 0.1 nm-100 mu m.

5. A method of making an integrated porous electrode according to any one of claims 1 to 4, wherein: the integrated porous electrode may be prepared as follows,

(1) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding a positive electrode material, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare positive electrode slurry;

(2) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding an inorganic ceramic electrolyte, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare electrolyte slurry;

(3) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding a negative electrode material, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare negative electrode slurry;

(4) pouring the anode slurry prepared in the step (1) on a smooth substrate, and carrying out blade coating to form a single-layer electrode, wherein the blade coating thickness is 50-1 cm, and preferably 1000-1 cm; pouring the electrolyte slurry prepared in the step (2) onto a single-layer electrode, adjusting the thickness of a scraper, and carrying out scraping coating to form a double-layer electrode, wherein the scraping coating thickness is 150-1.5 cm, preferably 2500-1.5 cm; pouring the negative electrode slurry prepared in the step (3) onto a double-layer electrode, adjusting the thickness of a scraper, blade-coating to form a three-layer electrode, wherein the blade-coating thickness is 200-2.5 cm, preferably 3500-2.5 cm, and then soaking the three-layer electrode into a poor solvent (coagulating bath) of high polymer resin for 5-600 s; or the scraping and coating sequence of the anode slurry and the cathode slurry can be changed, namely the anode slurry is scraped and coated firstly, then the electrolyte slurry is scraped and coated, and finally the cathode slurry is scraped and coated;

(5) washing the porous electrode prepared in the step (4) with water, freezing, shearing the electrode to a required shape and size in a frozen state, drying the sheared electrode in a freeze dryer, and vacuum-drying the electrode at 60-100 ℃ for more than 10 hours to obtain a dried porous electrode;

the freezing method can place the electrode in a freezing chamber of a refrigerator for more than 3 hours or put the electrode in liquid nitrogen for quenching, wherein the temperature of the freezing chamber of the refrigerator is-50 to-5 ℃;

the working temperature of the freeze dryer is-80 to-40 ℃, the pressure is 0 to 50Pa, and the drying time is 2 to 24 hours;

the organic solvent is one or more of dimethyl sulfoxide (DMSO), Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) and N, N-Dimethylformamide (DMF), and is preferably NMP;

the poor solvent of the resin is one or more of water, methanol, ethanol, propanol or isopropanol, and preferably water.

6. Use of an integrated porous electrode according to any of claims 1 to 4, wherein: the integrated porous electrode may be used in a lithium ion battery.

Technical Field

The invention relates to an integrated porous electrode for a lithium ion battery.

Background

The method reduces the dependence on fossil energy, vigorously develops renewable energy, improves the proportion of the renewable energy in an energy structure, and is a necessary choice for the development of human society. In order to realize effective utilization of renewable energy, development of efficient energy storage technology is crucial. Among various energy storage technologies, lithium ion batteries have rapidly developed and widely paid attention in recent decades due to their advantages of high energy density, long cycle life, small self-discharge coefficient, no memory effect, and the like.

With the expansion of the application range of lithium ion batteries, the development of novel electrode materials meeting development requirements becomes the key point of lithium ion battery research. Through the continuous efforts of researchers in recent years, the electrode material of the lithium ion battery is rapidly developed, and the performance of the lithium ion battery is continuously improved. However, the electrode structure is less developed, and the active material loading at the electrode has a serious influence on the performance of the battery.

The conventional method for preparing the electrode, namely the method for industrially preparing the electrode, is to scrape and coat electrode slurry on a carbon-coated aluminum foil, and prepare the electrode after drying a solvent in an oven. As the material shrinks and aggregates in the solvent volatilization process, the prepared electrode often cracks and even falls off from the aluminum foil along with the increase of the carrying capacity, so that the conductivity of the electrode is reduced. On the other hand, the reaction rate of the internal active material and lithium ions in the electrolyte is obviously slowed down due to the material agglomeration, and further the performance of the battery is reduced, especially the rate performance. In order to meet the market requirements of high energy density, fast charge and discharge and the like, the traditional electrode preparation method is not satisfactory, so that the electrode preparation method needs to be improved, a novel electrode structure needs to be designed, and the electron and ion transmission in the electrode needs to be improved. In response to this problem, three-dimensional electrode structures have been developed. The three-dimensional electrode is usually a continuous conductive carbon skeleton prepared by electrostatic spinning, vacuum filtration or direct carbonization. Although the electrode can effectively relieve the problem of hindered electron and ion transmission, the preparation method is difficult, the problem of strict material requirement and the like prevents the electrode from being applied in a large scale. In addition, the electrode porosity of such electrodes is high, and the increase in the electrolyte content in the electrode lowers the energy density of the battery as a whole. On the other hand, the traditional battery structure is formed by stacking a positive electrode, a negative electrode and a diaphragm, an electrolyte solution is filled in a battery system, and the contact resistance of the electrode structure at the interface of the positive electrode, the negative electrode and the diaphragm is large. Based on this, the invention proposes an elastic three-dimensional integrated electrode. Compared with the conventional electrode applied to the lithium ion battery, the integrated porous electrode has higher porosity and elasticity, and can be pressed and provided with a through pore structure, thereby effectively accelerating the ion transmission in the electrode and improving the multiplying power performance of the battery; in addition, the high polymer resin in the integrated electrode is continuous, so that the internal contact resistance of the battery is greatly reduced, and the capacity of the battery is improved; the positive electrode, the diaphragm and the negative electrode are simultaneously prepared, so that the electrode preparation process and the battery assembly process are simplified, and the preparation method is simple and easy to amplify; in addition, the integrated electrode does not need a current collector when in use, and has wide application prospect in the aspects of wearable and portable batteries. And in the phase inversion process, the high molecular resins are mutually crosslinked, so that the carbon/sulfur compound is tightly coated in the high molecular resins, the bonding property of the binder is improved, and the high molecular resins can be used for preparing high-load electrodes and are more beneficial to developing high-energy-density batteries. The integrated porous electrode is applied to the lithium ion battery, has great advantages in the aspects of electrode preparation process, battery performance and the like, and has good application prospect.

Disclosure of Invention

The invention aims to provide an integrated porous electrode for a lithium ion battery.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an integrated porous electrode is prepared by mixing organic polymer resin solution with positive electrode material, negative electrode material and inorganic ceramic electrolyte to form positive electrode slurry, negative electrode slurry and electrolyte slurry; and (2) coating the substrate with positive slurry, electrolyte slurry and negative slurry in sequence, or coating the substrate with negative slurry, electrolyte slurry and positive slurry in sequence, and preparing the integrated porous electrode with the positive electrode, the diaphragm and the negative electrode integrated into a whole by an immersion phase conversion method after coating.

The organic polymer resin can be one or more of Polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), Polystyrene (PS), polyvinyl alcohol (PVA), polyethylene glycol (PEG), polyvinylidene fluoride (PVDF), polyether sulfone (PES), Polybenzimidazole (PBI) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), and the mass content of the organic polymer resin in the organic polymer resin solution can be 2-70%;

the positive electrode material is a mixture of a positive electrode active material of the lithium ion battery and a conductive carbon material, wherein the content of the conductive carbon material accounts for 0-15% by mass and can be selected according to the conductivity of the material; the positive active material may be lithium cobaltate (LiCoO)₂) Lithium nickelate (LiNiO)₂) Lithium manganate (Li)_xMn_yO_z) Lithium iron phosphate (LiFePO)₄) And lithium vanadium phosphate (Li)₃V₂(PO4)₃) The mass ratio of the anode material to the organic polymer resin in the anode can be 1/1-9.5/1; the negative electrode material is a mixture of a lithium ion battery negative electrode active material and a conductive carbon material, wherein the conductive carbon material accounts for 0-15% of the mass ratio and can be selected according to the conductivity of the material; the negative active material can be one of graphite, amorphous carbon material, carbon nano tube, graphene, tin-based, silicon-based, titanium-based negative material and metal oxide (sulfide), and the mass ratio of the negative material to the organic polymer resin in the negative electrode can be 1/1-9.5/1; the conductive carbon material is one or more than two of carbon nano tube, graphene, carbon nano fiber, BP2000, KB600, KB300, XC-72, Super-P, acetylene black and active carbon;

the inorganic ceramic electrolyte can be silicon oxide (SiO)₂) Alumina (A1)₂O₃) Titanium oxide (TiO)₂) And barium titanate (BaTiO)₃) One ofThe mass ratio of the inorganic ceramic electrolyte to the organic polymer resin in the electrolyte can be 1/1-3/1.

The substrate can be a glass plate, a polytetrafluoroethylene plate or an aluminum foil.

The electrode comprises a positive electrode, an electrolyte diaphragm and a negative electrode, wherein the polymer resin is continuously crosslinked, the pore structure is continuous and through, and the porosity is higher and is 40-65%, preferably 50-60%; the aperture range is 0.1 nm-100 mu m.

The thickness of the positive and negative electrodes should be adjusted and controlled according to the release capacity of the active material (for example, LFP is selected as the active material for the positive electrode, the discharge capacity of the assembled single cell is 164mAh, at this time, the discharge capacity of the negative electrode is matched with 1.1 times of that of the positive electrode according to the discharge capacity of the negative electrode, the discharge capacity of the negative electrode should be 180mAh, and the discharge specific capacity of the assembled single cell with graphite as the active material is 300mAh g^-1Therefore, the carrying capacity of the negative active material, namely the scraping coating thickness, needs to be regulated and controlled, so that the discharge capacity of the negative electrode reaches 180 mAh); when the loading capacity of the anode and cathode active materials is larger, the thickness of the electrolyte diaphragm is increased in a proper amount.

The preparation process of the integrated porous electrode is as follows:

(1) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding a positive electrode material, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare positive electrode slurry;

(2) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding an inorganic ceramic electrolyte, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare electrolyte slurry;

(3) adding organic polymer resin into an organic solvent, stirring for 0.5-2 hours at the temperature of 20-50 ℃ to form a polymer solution, adding a negative electrode material, and fully stirring for 2-10 hours at the temperature of 20-50 ℃ to prepare negative electrode slurry;

(4) (4) pouring the positive electrode slurry prepared in the step (1) on a smooth substrate, and forming a single-layer electrode after blade coating, wherein the blade coating thickness is 50-1 cm, and is preferably 1000-1 cm; pouring the electrolyte slurry prepared in the step (2) onto a single-layer electrode, adjusting the thickness of a scraper, and carrying out scraping coating to form a double-layer electrode, wherein the scraping coating thickness is 150-1.5 cm, preferably 2500-1.5 cm; pouring the negative electrode slurry prepared in the step (3) onto a double-layer electrode, adjusting the thickness of a scraper, blade-coating to form a three-layer electrode, wherein the blade-coating thickness is 200-2.5 cm, preferably 3500-2.5 cm, and then soaking the three-layer electrode into a poor solvent (coagulating bath) of high polymer resin for 5-600 s; or the scraping and coating sequence of the anode slurry and the cathode slurry can be changed, namely the anode slurry is scraped and coated firstly, then the electrolyte slurry is scraped and coated, and finally the cathode slurry is scraped and coated;

(5) washing the porous electrode prepared in the step (4) with water, freezing, shearing the electrode in a frozen state, drying the sheared electrode in a freeze dryer, and vacuum-drying the electrode at 60 ℃ for 10 hours or more to obtain a dried porous electrode; the freezing method can be characterized in that the electrode can be placed in a freezing chamber of a refrigerator for 3 hours or more or placed in liquid nitrogen for quenching, the temperature of the freezing chamber of the refrigerator is less than-5 ℃, the working temperature of a freeze dryer is-40 ℃ or less, the pressure is less than 25Pa, and the drying time is 2-24 hours;

the organic solvent is one or more of dimethyl sulfoxide (DMSO), Dimethylacetamide (DMAC), N-methylpyrrolidone (NMP) and N, N-Dimethylformamide (DMF), and is preferably NMP;

the poor solvent of the resin is one or more of water, methanol, ethanol, propanol or isopropanol, and preferably water.

The integrated porous electrode may be used in a lithium ion battery.

The beneficial results of the invention are:

(1) the integrated porous electrode prepared by the invention has higher porosity and a through pore structure, effectively accelerates the ion transmission in the electrode and can improve the rate capability of the battery;

(2) the high molecular resin in the integrated porous electrode prepared by the invention forms a continuous through porous network structure in the phase inversion process, provides a more continuous channel for lithium ion transmission, and accelerates the transmission rate; and the integrated electrode can greatly reduce the internal contact resistance of the battery.

Compared with the conventional direct drying preparation method of the electrode, the integrated electrode preparation method improves the bonding property of the electrode, can prepare a high-carrying-capacity electrode and prepare a high-energy-density battery;

(3) the invention prepares the porous electrode with the positive electrode, the diaphragm and the negative electrode integrated, simplifies the electrode preparation process and the battery assembly process, and the preparation method is simple and easy to enlarge;

(4) the integrated electrode prepared by the invention does not need a current collector when in use, and has wide application prospect in the aspects of wearable and portable batteries;

drawings

FIG. 1: example 1 cross-sectional SEM image (a), surface SEM image (b), comparative example cross-sectional SEM image (c), and surface SEM image (d);

FIG. 2: rate performance test at 0.2C-10C of the lithium ion full cell assembled by the example 1 and the example 2 and the comparative examples 1, 6 and 7;

FIG. 3: rate performance test at 0.2C-20C of the lithium ion full cell assembled in example 4;

Detailed Description

The following examples are further illustrative of the present invention and are not intended to limit the scope of the present invention.

Example 1

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PVDF solution (10% by weight) are weighed in, 0.2g of titanium dioxide (TiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 200 mu m, blade-coating the negative electrode slurry on an aluminum foil to form a single-layer electrode, adjusting the scraper to 1000 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 1400 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; rapidly immersing the three-layer electrode in water for 10min, taking out, cleaning with water, automatically dropping off the electrode from aluminum foil in the process, observing the electrode aperture range from 0.1nm to 100 μm from SEM image, placing the electrode in refrigerator freezer (temperature-10 deg.C) for 5h, maintaining the electrode in frozen state, and cuttingCutting into small discs with the diameter of 14mm, and drying the cut electrodes in a freeze dryer (working temperature is minus 45 ℃ and working pressure is 20Pa) for 10h to form the self-supporting integrated electrode. And (3) drying the dried electrode in vacuum at 60 ℃ for 24h to obtain the integrated electrode. LBC3707D is used as electrolyte solution to assemble the battery, and the loading amount of positive active material is about 4mg cm^-2And calculating, and carrying out a multiplying power performance test at a multiplying power of 0.2-10C.

The first-circle discharge specific capacity is 164mA h g under the 0.2C multiplying power^-1When the multiplying power is increased to 10C, the specific discharge capacity is 40mA h g^-1。

Example 2 (porosity influence)

Weighing 4g of PVDF solution (10 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (10 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PVDF solution (20% by weight) are weighed in, 0.2g of titanium dioxide (TiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 100 mu m, blade-coating the negative electrode slurry on a dry smooth clean glass plate to form a single-layer electrode, adjusting the scraper to 500 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 700 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. The electrode is placed in a freezing chamber (the temperature is minus 10 ℃) of a refrigerator for 5 hours, the electrode is cut into small round pieces with the diameter of 14mm in a freezing state, and then the cut electrode is placed in a freezing dryer (the working temperature is minus 45 ℃ and the working pressure is 20Pa) for drying for 10 hours to form the self-supporting integrated electrode. And (3) drying the dried electrode in vacuum at 60 ℃ for 24h to obtain the integrated electrode. LBC3707D is used as electrolyte solution to assemble the battery, and the loading amount of positive active material is about 4mg cm^-2And calculating, and carrying out a multiplying power performance test at a multiplying power of 0.2-10C.

The first-circle discharge specific capacity is 164mA h g under the 0.2C multiplying power^-1When the multiplying power is increased to 10C, the specific discharge capacity is 29mA h g^-1。

Example 3 (porosity influence)

Weighing 4g of PVDF solution (20 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (20 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PVDF solution (25% by weight) are weighed in, 0.2g of titanium dioxide (TiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 80 mu m, blade-coating the negative electrode slurry on a dry smooth clean glass plate to form a single-layer electrode, adjusting the scraper to 500 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 660 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. The electrode is placed in a freezing chamber (the temperature is minus 10 ℃) of a refrigerator for 5 hours, the electrode is cut into small round pieces with the diameter of 14mm in a freezing state, and then the cut electrode is placed in a freezing dryer (the working temperature is minus 45 ℃ and the working pressure is 20Pa) for drying for 10 hours to form the self-supporting integrated electrode. And (3) drying the dried electrode in vacuum at 60 ℃ for 24h to obtain the integrated electrode. LBC3707D is used as electrolyte solution to assemble the battery, and the loading amount of positive active material is about 4mg cm^-2And calculating, and carrying out a multiplying power performance test at a multiplying power of 0.2-10C.

The first-circle discharge specific capacity is 164mA h g under the 0.2C multiplying power^-1When the multiplying power is increased to 10C, the specific discharge capacity is 24mA h g^-1。

Example 4 (other active substance)

1g of PBI was dissolved in 9g N-methylpyrrolidone (NMP) and stirred for 5 hours to prepare a 10 wt% PVDF solution.

1g of PBI was dissolved in 19g N-methylpyrrolidone (NMP) and stirred for 5 hours to prepare a 5 wt% PVDF solution.

4g of PBI solution (5% by weight) were weighed out and 0.7g of lithium vanadium phosphate (Li) were added₃V₂(PO4)₃) And 0.1g of Super P, stirring for 5 hours to prepare anode slurry; weighing 4g of PBI solution (5 wt%), adding 0.7g of carbon nano tube and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PBI solution (10 wt%) are weighed in and 0 is added2g of Silica (SiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 50 mu m, blade-coating the negative electrode slurry on a dry smooth clean polytetrafluoroethylene plate to form a single-layer electrode, adjusting the scraper to 250 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 330 mu m, blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. The electrode is placed in a freezing chamber (the temperature is minus 10 ℃) of a refrigerator for 5 hours, the electrode is cut into small round pieces with the diameter of 14mm in a freezing state, and then the cut electrode is placed in a freezing dryer (the working temperature is minus 45 ℃ and the working pressure is 20Pa) for drying for 10 hours to form the self-supporting integrated electrode. And (3) drying the dried electrode in vacuum at 60 ℃ for 24h to obtain the integrated electrode. LBC3707D was used as an electrolyte solution to assemble a battery, and the loading of the positive electrode active material was about 1.5mg cm^-2And calculating, and carrying out a multiplying power performance test at a multiplying power of 0.2-20C.

The first-circle discharge specific capacity is 122mA h g under the 0.2C multiplying power^-1When the multiplying power is increased to 20C, the specific discharge capacity is 102mA h g^-1。

Examples 5 to 8 were otherwise the same as in example 1 except that the conductive carbon and the mass ratio thereof in the electrode were adjusted and the battery performance was measured as follows, unlike example 1.

The pore diameters of the electrodes of examples 1 to 8 were all in the range of 0.1nm to 100. mu.m.

Comparative example 1

1g of polyvinylidene fluoride (PVDF) was dissolved in 4g N-methylpyrrolidone (NMP) and stirred for 5 hours to prepare a 20 wt% PVDF solution.

1g of polyvinylidene fluoride (PVDF) was dissolved in 9g N-methylpyrrolidone (NMP) and stirred for 5 hours to prepare a 10 wt% PVDF solution.

1g of polyvinylidene fluoride (PVDF) was dissolved in 19g N-methylpyrrolidone (NMP) and stirred for 5 hours to prepare a 5 wt% PVDF solution.

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, stirring for 5h, adjusting a scraper to 400 mu m, blade-coating on an aluminum film to form a film, drying at 70 ℃ overnight, shearing into small round pieces with the diameter of 14mm, weighing, drying at 60 ℃ in vacuum for 24h to prepare a positive plate, wherein the loading capacity of an electrode active substance is about 4mg cm^-2. Weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, stirring for 5h, adjusting a scraper to 200 mu m, blade-coating a copper film to form a film, drying at 70 ℃ overnight, shearing into small round pieces with the diameter of 14mm, weighing, drying at 60 ℃ in vacuum for 24h to prepare a negative plate, wherein the loading capacity of a positive active substance is about 2mg cm^-2. The clegard 2325 is taken as a diaphragm, the LBC3707D is taken as electrolyte solution, the battery is assembled, and the rate performance test is carried out under the rate of 0.2C-10C.

The first-circle specific discharge capacity under 0.2C multiplying power is 162mA h g^-1When the multiplying power is increased to 10C, the specific discharge capacity is 23mA h g^-1。

In order to increase the loading of the positive active material, the scraping thickness of the positive slurry is increased as much as possible.

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, stirring for 5h, adjusting a scraper to 1000 mu m, blade-coating on an aluminum film to form a film, drying at 70 ℃ overnight, shearing into small round pieces with the diameter of 14mm, weighing, drying at 60 ℃ in vacuum for 24h to prepare a positive plate, wherein the loading capacity of an electrode active substance is about 4mg cm^-2. Weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, stirring for 5h, adjusting a scraper to 500 mu m, blade-coating a copper film to form a film, drying at 70 ℃ overnight, shearing into small round pieces with the diameter of 14mm, weighing, drying in vacuum at 60 ℃ for 24h to prepare a negative plate, and finding that the positive plate electrode cracks, the active substance falls off, and the material is mainly agglomerated due to solvent volatilization in the drying process. It is obvious that the conventional electrode drying method in the prior art can not realize high loadA loading of positive electrode material.

Comparative example 2 (shear electrode after drying)

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PVDF solution (10% by weight) are weighed in, 0.2g of titanium dioxide (TiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 200 mu m, blade-coating the negative electrode slurry on an aluminum foil to form a single-layer electrode, adjusting the scraper to 1000 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 400 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. And (3) drying the electrode in a freeze dryer (working temperature is minus 45 ℃ and working pressure is 20Pa) for 10 hours to form the self-supporting integrated electrode. And cutting the dried electrode into small round pieces with the diameter of 14mm, weighing, and carrying out vacuum drying at 60 ℃ for 24h to obtain the integrated electrode. LBC3707D is used as electrolyte solution to assemble the battery, and the loading amount of positive active material is about 4mg cm^-2And calculating, and carrying out a multiplying power performance test at a multiplying power of 0.2-10C. The positive electrode, the electrolyte and the negative electrode of the integrated electrode are integrated, the electrode collapses due to the existence of shearing force after being dried and sheared, and the residues of the positive electrode and the negative electrode are mutually connected and contacted, so that the assembled battery is short-circuited.

Comparative example 3 (without solid electrolyte)

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; adjusting a scraper to 200 mu m, blade-coating the negative electrode slurry on an aluminum foil to form a single-layer electrode, adjusting the scraper to 1000 mu m, blade-coating 10 wt% of PVDF solution on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 400 mu m, blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. And (3) drying the electrode in a freeze dryer (working temperature is minus 45 ℃ and working pressure is 20Pa) for 10 hours to form the self-supporting integrated electrode. And (3) drying the dried electrode in vacuum at 60 ℃ for 24h to obtain the integrated electrode. The electrolyte layer has no support substance, the prepared electrode has serious wrinkles due to serious contraction of the electrolyte layer in the phase conversion process, a diaphragm cannot effectively separate a positive electrode material from a negative electrode material, the integrated electrode collapses, the loading amount of an active substance cannot be estimated, LBC3707D is used as an electrolyte solution, a battery is assembled, and the battery is short-circuited.

Comparative example 4 (mismatch of anode, cathode and electrolyte)

Weighing 4g of PVDF solution (10 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PVDF solution (10% by weight) are weighed in, 0.2g of titanium dioxide (TiO)₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 200 mu m, blade-coating the negative electrode slurry on an aluminum foil to form a single-layer electrode, adjusting the scraper to 1000 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 400 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, and cleaning with water, wherein the electrode can automatically fall off from the aluminum foil in the process. And (3) drying the electrode in a freeze dryer (at a working temperature of-45 ℃ and a working pressure of 20Pa) for 10h to form a self-supporting electrode, wherein the proportion of the cathode binder is inconsistent with that of the anode and the electrolyte, the contraction proportions of the cathode, the anode and the electrolyte layer are inconsistent in the phase conversion process, the electrode wrinkles are serious, the anode and the cathode materials cannot be effectively separated by a diaphragm, the integrated electrode collapses, and the battery cannot be assembled.

COMPARATIVE EXAMPLE 5 (Adhesives of different types)

Weighing 4g of PVDF solution (10 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, and stirring for 5 hours to prepare anode slurry; weighing 4g of PVDF solution (10 wt%), adding 0.7g of graphite and 0.1g of Super P, and stirring for 5 hours to prepare negative electrode slurry; 4g of PBI solution (20% by weight) are weighed out and 0.2g of titanium dioxide are added(TiO₂) Stirring for 5 hours to prepare electrolyte slurry; adjusting a scraper to 100 mu m, blade-coating the negative electrode slurry on a dry smooth clean glass plate to form a single-layer electrode, adjusting the scraper to 500 mu m, blade-coating the electrolyte slurry on the single-layer electrode to form a double-layer electrode, then adjusting the scraper to 200 mu m, and blade-coating the positive electrode slurry on the double-layer electrode to form a three-layer electrode; and quickly immersing the three-layer electrode into water, taking out after 10min, washing with water, and drying the electrode in a freeze dryer (working temperature is minus 45 ℃ and working pressure is 20Pa) for 10h to form a self-supporting integrated electrode.

Comparative example 6 (three layers of slurry made porous structure, assembled into electrode structure)

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, stirring for 5 hours, adjusting a scraper to 400 mu m, blade-coating an aluminum film to form a film, quickly immersing the film in water, taking out the film after 10min, washing the film with water, drying the film at 25 ℃ for 12 hours, automatically dropping the film from the aluminum foil in the process, shearing the film into small wafers with the diameter of 14mm, weighing, drying the wafers in vacuum at 60 ℃ for 24 hours to prepare positive plates, wherein the loading capacity of electrode active substances is about 4mg cm^-2. Weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, stirring for 5h, adjusting a scraper to 200 mu m, quickly immersing the PVDF solution into water, taking out after 10min, washing with water, drying at 25 ℃ for 12h, automatically dropping a film from an aluminum foil in the process, shearing the film into small wafers with the diameter of 14mm, weighing, drying at 60 ℃ for 24h in vacuum to prepare a negative plate, wherein the loading capacity of an electrode active substance is about 2mg cm^-2. The clegard 2325 is taken as a diaphragm, the LBC3707D is taken as electrolyte solution, the battery is assembled, and the rate performance test is carried out under the rate of 0.2C-10C.

The first-circle specific discharge capacity under 0.2C multiplying power is 156mA h g^-1When the multiplying power is increased to 10C, the specific discharge capacity is 12mA h g^-1。

The expected results are: the internal resistance is large, and the connectivity of the hole is not good, so that the transmission of electrons and ions is blocked, and the performance of the battery is reduced.

Comparative example 7

Weighing 4g of PVDF solution (5 wt%), adding 0.7g of lithium iron phosphate (LFP) and 0.1g of Super P, stirring for 5 hours, adjusting a scraper to 400 mu m, blade-coating an aluminum film to form a film, quickly immersing the film in water, taking out the film after 10min, washing the film with water, drying the film at 25 ℃ for 12 hours, automatically dropping the film from the aluminum foil in the process, shearing the film into small wafers with the diameter of 14mm, weighing, drying the wafers in vacuum at 60 ℃ for 24 hours to prepare positive plates, wherein the loading capacity of electrode active substances is about 4mg cm^-2. Weighing 4g of PVDF solution (5 wt%), adding 0.7g of graphite and 0.1g of Super P, stirring for 5h, adjusting a scraper to 200 mu m, quickly immersing the PVDF solution into water, taking out after 10min, washing with water, drying at 25 ℃ for 12h, automatically dropping a film from an aluminum foil in the process, shearing the film into small wafers with the diameter of 14mm, weighing, drying at 60 ℃ for 24h in vacuum to prepare a negative plate, wherein the loading capacity of an electrode active substance is about 2mg cm^-2. 4g of PVDF solution (10% by weight) are weighed in, 0.72g of titanium dioxide (TiO)₂) Stirring for 5h, adjusting a scraper to 800 mu m, blade-coating on a smooth glass plate to form a film, quickly immersing in water, taking out after 10min, washing with water, drying at 25 ℃ for 12h, automatically dropping the film from the glass plate in the process, shearing into small wafers with the diameter of 19mm, vacuum drying at 60 ℃ for 24h to prepare diaphragm sheets, taking the diaphragm sheets as diaphragms, taking LBC3707D as electrolyte solution, assembling the battery, and carrying out multiplying power performance test at the multiplying power of 0.2-10C.

The first-circle specific discharge capacity under 0.2C multiplying power is 160mA h g^-1When the multiplying power is increased to 10C, the specific discharge capacity is 12mA h g^-1。

The expected results are: the internal resistance is large, and the connectivity of the hole is not good, so that the transmission of electrons and ions is blocked, and the performance of the battery is reduced. The performance of the separator is similar to that of the separator using the celgard.

In the phase inversion process, the polymer resin is cured to form a continuous pore structure, and the electrode material is wrapped inside the continuous pore structure, so that an integrated porous electrode is obtained. From the cross-sectional SEM (FIG. 1a) of example 1, it is evident that the three-layer structure is seen, the lowest layer being the negative electrode (graphite) and the middle white being TiO₂An electrolyte layer, an upper layer of positive electrode (LFP), IIIThe layers are tightly combined without fault phenomenon, which shows that the three layers are integrated, namely, an integrated electrode. The porosity of the electrode is 57%, the aperture range is 0.5 nm-50 μm, the thickness of the anode is about 350 μm, and the thickness of the cathode is about 70 μm; the thickness of the electrolyte diaphragm is 200 μm, and the finger-shaped holes formed by phase inversion penetrate through the electrode, so that a rapid transmission channel is provided for ion transmission, and the rate performance of the battery is improved. In comparison with the SEM images of the surfaces of comparative example 1 and example 1, the surface of example 1 is flat and has no cracks, and the pore structure is uniformly distributed, while comparative example 1 has severe cracks on the surface of the electrode due to thermal shrinkage of the polymer resin during the drying process. Because the positive electrode, the electrolyte and the negative electrode of the integrated electrode are integrated, the positive and negative electrode materials are easy to contact and cause short circuit of the assembled battery due to the existence of shearing force when the electrode is sheared after being dried, as in comparative example 2, the shearing of the electrode in a frozen state is very important in the electrode preparation process. In addition, the addition of the solid electrolyte and the solid contents of the cathode paste, the electrolyte paste and the anode paste are carefully adjusted. The polymer resin solution was instantaneously phase-separated in the non-solvent to have a porous structure, and at this time, a volume change was accompanied, and when the solid electrolyte was not added, the intermediate separator was significantly shrunk due to no support structure, resulting in severe surface wrinkles of the prepared electrode, and the prepared electrode-assembled battery was short-circuited, as shown in comparative example 3. If the solid content between the positive electrode slurry, the electrolyte slurry and the negative electrode slurry is too different, mismatching can also cause electrode wrinkles, which is not favorable for practical application, such as comparative example 4, and furthermore, the polymer resin type mismatching can also cause different solvent exchange rates in the phase inversion process, different curing speeds of the polymer resin, and electrode wrinkles, which is not favorable for practical application, such as comparative example 5.

Based on the above characteristics, as shown in fig. 3, in the battery using the positive electrode material of example 1, the specific discharge capacity of the first loop is 164mA h g at 0.2C rate^-1Above, slightly higher than that of comparative example (162mA h g)^-1) The specific discharge capacity is up to 40mA h g at the multiplying power of 10C^-1(ii) a Much higher than in comparative example (23mA h g)^-1). From examples 1 to 3, it can be seen that the polymer resin mass content used for preparing the positive and negative electrode pastes was adjusted to the specific electric potentialThe influence of the polar porosity is large, when the polymer resin is PVDF, the content is preferably 5 wt%, and the prepared electrode (example 1) has a large porosity of 57% and rich pore structures, so that sufficient lithium ions can be provided for reaction, and the rate capability of the battery is improved. The conductive carbon content in the electrode affects the conductivity of the electrode, the more conductive carbon is added, the better the conductivity of the electrode is, and the better the battery performance is, however, in order to pursue high energy density, the conductive carbon content in the electrode should not be too high (as can be seen in examples 1,5, 6), and when the conductive carbon is Super P, 12.5 wt% is preferred. Differences in the conductivity and specific surface area of the different conductive carbons themselves can affect the conductivity and porosity of the electrodes and thus the cell performance, as shown in example 7. Increasing the active material loading (example 8), the integrated electrode still provided rapid ion transport and the performance of the cell was slightly degraded.

In addition, the preparation method of the electrode is suitable for various electrode materials, and in example 4, the lithium vanadium phosphate is used as a positive electrode active material, the silicon dioxide is used as a solid electrolyte, and the hard carbon is used as a negative electrode to prepare an integrated electrode; the first-circle specific discharge capacity of the battery assembled by the lithium ion battery is 122mA h g under the discharge rate of 0.2C^-1When the multiplying power is increased to 20C, the specific discharge capacity is 102mA h g^-1It showed excellent rate performance, as shown in fig. 3.