CN112133882B - Solvent-free preparation method of electrode for electrochemical energy storage device - Google Patents

Abstract

A solvent-free preparation method of an electrode for an electrochemical energy storage device comprises the steps of placing polymer binder powder in an electric polarization device, and performing electric polarization treatment on the polymer binder to obtain an electric polarization polymer binder; uniformly mixing the polymer binder subjected to electret polarization, the electrode active substance and the conductive agent in mixing equipment to obtain an electrode master batch; placing the electrode master batch into a briquetting machine, placing the electrode master batch into a plunger type extruder after briquetting, and extruding an electrode master batch sample strip; rolling the electrode master batch sample strip in a calender to form an electrode master batch membrane; and placing the electrode master batch membrane in vapor deposition equipment, and depositing a layer of metal collector with the thickness of 10 nm-5 mu m on the surface of the electrode master batch. The electrode master batch has good dispersibility, the manufactured electrode diaphragm has good uniformity, high density and mechanical strength, and easy processing and forming, and the formed electrode has good electrochemical stability, solvent resistance and mechanical property, and has good cycle service life and specific capacitance.

Description

A solvent-free preparation method of electrodes for electrochemical energy storage devices

technical field

The invention belongs to the field of electrode preparation, and in particular relates to a solvent-free preparation method of electrodes for electrochemical energy storage devices.

Background technique

Electrodes provide sites for charge storage/release and become key core components of electrochemical energy storage devices such as Li-ion batteries, supercapacitors, and Li-ion capacitors. Electrode preparation methods can be divided into wet and dry methods. The wet method is to mix the electrode active material, conductive agent and binder in water or organic solvent to obtain a viscous slurry; then it is combined with the metal collector by roller coating, scraping and spraying; Processes such as rolling, drying and finishing remove solvents to obtain electrodes. Wet preparation of electrodes has the advantages of uniform mixing of electrode components, simple process and strong continuity, but there are also disadvantages such as large water/solvent residues, binder blocking charge channels, and low volume-to-volume energy storage density. The dry electrode preparation process is to use the electrode active material, conductive agent and binder to obtain a uniformly mixed electrode masterbatch through the mixing equipment; The particles form an electrode master material diaphragm; finally, the electrode master material diaphragm is combined with a metal collector through a conductive adhesive to obtain an electrode. The dry process has the advantages of no solvent residue, high utilization of electrode active materials and wide adjustable range of electrode thickness, and has become an advanced electrode preparation method.

CN109755473 A discloses a dry method for preparing lithium battery electrodes. The method is to uniformly mix and finely pulverize the electrode materials, and form electrode film strips by multi-pass high-temperature rolling, and then compound them to a sticky film strip by high-temperature rolling. Mixture-coated metal foil strips, and finally get rolled electrodes. CN105225847 A discloses a preparation method of a dry-process electrode for an electric double-layer capacitor. The method is to combine powdered activated carbon, binder polytetrafluoroethylene powder, and a conductive agent with high-speed airflow mixing technology to realize solid powder particles. At the same time, with the help of the deformation structure of PTFE under high-speed shear conditions, the active material, conductive agent, and binder are mixed to obtain electrode sheets for supercapacitors. Both of the above two methods use a dry method to make electrodes, but these two methods use the electrode masterbatch powder to be directly rolled to form an electrode diaphragm, which has the disadvantages of poor uniformity, low density and low mechanical strength of the electrode.

CN102629681 A discloses a preparation method of a dry-process electrode. The method is to uniformly mix the powder active material, the powder conductive agent and the powder binder through a three-dimensional powder mixer or a gravity-free powder mixer, and then pass the low-temperature The pulverizer is crushed, and then it is extruded through a twin-screw extruder or an internal mixer/open mill, and then hot-pressed by a calender to reach the target thickness. Finally, it is combined with a three-layer current collector of printed conductive adhesive to form an electrode and Cold rolling increases compaction density. CN101894676 A discloses a method for preparing a diaphragm for supercapacitor electrode sheets, the method is to extrude carbon black, linear low-density polyethylene, and activated carbon powder through twin-screws to be a pasty soft core blank in the shell, and then , and the electrodes are obtained through processes such as rolling, finish rolling and crimping. The above two methods also use the dry method to make electrodes, but the polymer binder agglomeration in these two methods cannot be completely opened, resulting in a low degree of dispersion between the electrode materials; the polymer binder has a large molecular weight and low viscosity during the screw extrusion process. The content of high and electrode active powders is high, which leads to problems such as difficulty in conveying the masterbatch during the screw extrusion process, easy slippage of the material, and large equipment loss. Moreover, due to frictional heat generation, the powder may also adhere to the screw or barrel. , making the feeding more difficult and unstable; the conductive glue connecting the electrode masterbatch diaphragm and the collector has insufficient electrochemical stability, solvent resistance and mechanical properties, which will affect the cycle life of the electrochemical device, and it belongs to Non-electrode active materials will reduce the specific capacitance of electrochemical energy storage devices.

Contents of the invention

The technical problem to be solved by the present invention is to provide a solvent-free preparation method for electrodes for electrochemical energy storage devices. The electrode masterbatch has good dispersibility, and the prepared electrode diaphragm has good uniformity, high density and high mechanical strength, and is easy to process and shape. The formed electrode has good electrochemical stability, solvent resistance and mechanical properties, and has good cycle life and specific capacitance.

Technical scheme of the present invention is:

A solvent-free preparation method of an electrode for an electrochemical energy storage device, the specific steps of which are as follows:

(1) Polymer binder electroelectretization

Taking the polymer binder powder and placing it in an electric polarization device, performing electroelectretization treatment on the polymer binder to obtain an electroelectretized polymer binder;

(2) Preparation of electrode masterbatch

placing the electroelectretized polymer binder, the electrode active material, and the conductive agent in a mixing device and mixing them uniformly to obtain an electrode masterbatch;

(3) Preparation of electrode masterbatch diaphragm

Put the electrode masterbatch in the compacting machine, after compaction, put it in the plunger extruder, extrude the electrode masterbatch sample; then roll the electrode masterbatch sample in the calender to a thickness of 50μm ～5mm, width 100mm～1000mm electrode masterbatch diaphragm;

(4) Electrode masterbatch membrane deposition metal preparation electrode

The electrode master material diaphragm is placed in a vapor deposition device, and a layer of metal collector with a thickness of 10nm to 5 μm is deposited on the surface of the electrode master material at a deposition temperature of 80°C to 200°C.

Further, the number average molecular weight of the polymer binder is 2 million to 10 million, and the particle size is 20 nm to 50 μm.

Further, the polymer binder is at least one of polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride, and polytetrafluoroethylene-hexafluoropropylene copolymer.

Further, during electroelectretization treatment, one of electrospinning, corona discharge, triboelectrification, thermal polarization, and low-energy electron beam bombardment is used for treatment.

Further, when using electrospinning electroelectretization treatment, the spinning voltage is 15kV, the spinning distance is 10cm, and the spinning speed is 2.0mL/h;

When corona discharge electroelectretization is used, the mesh grid voltage is 10kV, the discharge distance is 1cm, and the processing speed is 800cm ² /min; when thermal polarization electroelectretization is used, the polymer binder is evenly spread on the Form a treatment layer with a thickness of 1mm and a width of 100mm on the surface of the copper plate for heat treatment. The heat treatment temperature is 120°C, the polarization electric field strength is 150MV/m, and the polarization speed is 600cm ² /min.

Further, the mixing equipment is at least one of a high-speed mixer, a V-type mixer, a gravity-free mixer, a three-dimensional mixer, a ball mill, an open mill, an internal mixer, and a jet mill; The temperature ranges from 0°C to 200°C, and the mixing time ranges from 1 min to 60 min.

Further, the electrode active material is at least one of lithium salts, carbon-based porous materials, graphite-based electrode materials, metal oxides, etc., and the particle size _D50 is 5 μm to 50 μm; the conductive agent is carbon aerogel, At least one of conductive carbon black, flake graphite, carbon nanotubes, graphene, and spherical graphite, the mass ratio of the polymer binder to the electrode active material and the conductive agent is 200:1700:100.

Further, the compacting conditions are that the pressure is 1.0MPa-10.0MPa, the compaction speed is 5mm/min-50mm/min, the holding time is 5s-10s, and the compaction temperature is 20°C-120°C;

The plunger type extruder is one of vertical type, horizontal type, single column type, double plunger type, continuous type or intermittent type, and the extrusion conditions of the plunger type are: extrusion speed is 10mm/min～100mm/min min, the extrusion temperature is 30°C-310°C, the compression ratio (RR) is 50-500, the length-to-diameter ratio (L/D) is 5-50, the cone angle (α) is 10°-90°, the extruded The electrode masterbatch spline is one of rod shape, rectangle shape, strip shape or tube shape;

The calender has 2-5 rolls, the aspect ratio is 2.0-3.0, the rolling speed is 1m/min-10m/min, and the roll temperature is 20°C-200°C.

The vapor deposition equipment is one of magnetron sputtering equipment, evaporation deposition equipment, ion plating equipment, pulse deposition equipment, and atomic layer deposition equipment; the material of the metal collector is copper, aluminum, silver, gold, platinum, etc. one or more of them.

When using the magnetron sputtering deposition method to deposit aluminum metal collectors, the purity of the aluminum target is ≥99.99%, the substrate temperature is 200°C, the argon gas pressure is 4×10 ^-3 Torr, the bias voltage is -500V, and the deposition rate is 50nm /min, the sputtering time is 60min; when the metal silver collector is deposited by evaporation deposition, the purity of the silver target is ≥99.99%, the substrate temperature is 120°C, the evaporation current is 500A, and the deposition thickness is 5μm;

When depositing metal copper collectors by atomic layer deposition, bis(hexafluoroacetylacetonate) copper is used as a precursor, the deposition temperature is 120°C, the input power is 300W, the deposition rate is 0.1nm/cycle, and the deposition thickness is 2μm.

The present invention first adopts the electric polarization method, after obtaining the polymer binder of electroelectretization, mixes the polymer binder of electroelectretization with electrode active material, conductive agent etc. evenly, obtains electrode masterbatch; Secondly, After the electrode masterbatch is passed through the plunger extruder to prepare the electrode masterbatch sample, the electrode masterbatch sample is rolled to form an electrode masterbatch diaphragm; finally, the electrode is prepared by vapor deposition metal collector method. Its beneficial effect is:

1. Improve the dispersion uniformity between the electrode masterbatches by electro-electrifying the polymer binder. Since the electroelectretized polymer binder itself has the same charge, the electrostatic repulsion can weaken the cohesion and the degree of agglomeration between the molecular chains of the polymer binder, thereby improving its dispersibility; and, the electroelectretized The polymer binder is more easily adsorbed to the surface of electrode active materials and conductive agent particles, and improves the uniformity of mixing and dispersion between electrode materials.

2. It is prepared from solvent-free electrode masterbatch diaphragm by plunger extrusion method, which has simple process, strong controllability and good product quality. The electrode masterbatch blanking process is beneficial to eliminate the gas between the masterbatch particles, improve the contact between the particles and the density of the electrode masterbatch diaphragm; the plunger extrusion process is beneficial to the solvent-free type with high viscosity, low fluidity and high inorganic particle content. Extrusion processing of electrode masterbatch; the plunger extrusion process can effectively control the degree of fibrosis of the polymer binder, which is beneficial to the rolling and forming processing of the electrode diaphragm, and the mechanical strength and density of the electrode masterbatch diaphragm are improved.

3. Depositing metal collectors on electrode masterbatch diaphragms can improve electrode quality. The metal collector is deposited on the surface of the electrode master material diaphragm by vapor deposition method, and the high adhesion of the metal deposition layer is used, the high porosity of the electrode master material diaphragm, the rough irregular surface and the fibrous network structure of the polymer binder and other characteristics, can obtain the interface between the metal collector with high bonding strength and the electrode active material, and improve the cycle life of the electrode; the metal collector with a nanometer thickness reduces the metal content of no charge storage capacity, which is conducive to improving the electrochemical storage capacity. The specific capacitance of the energy device; there is no need for a binder between the electrode diaphragm and the metal collector, which can remove the constraint of the binder on the electrochemical cycle stability, and can increase the mass ratio of the electrode active material in the electrode, which is beneficial to Improvement of specific capacitance of electrochemical energy storage devices.

Description of drawings

Fig. 1 is a process flow diagram of the present invention;

Fig. 2 is the scanning electron micrograph before and after the electric polarization of polytetrafluoroethylene binder of the present invention (corresponding embodiment 1);

Fig. 3 is the scanning electron micrograph of the electrode masterbatch that polymer binder prepares before and after electroelectretization of the present invention (corresponding embodiment 1);

Fig. 4 is the scanning electron micrograph of the calendering and rolling diaphragm of the electrode masterbatch of the present invention (corresponding to Example 1) directly calendering the diaphragm and the plunger extruder extruding the spline;

Fig. 5 Optical photo of metallic aluminum deposited on electrode masterbatch diaphragm;

Fig. 6 is the test curves of the specific capacity retention rate of the cycle charging and discharging of the embodiment 1 and the comparative example 1.

Detailed ways

Example 1

The process flow is shown in Figure 1, and the specific preparation steps are as follows:

1. Electrostatic polarization of PTFE binder

The electroelectretization of PTFE binder particles (Fig. 2a) was carried out by corona discharge method. Take 400 g of polytetrafluoroethylene binder particles with a particle size of 20 nm and a molecular weight of 10 million, and evenly spread them into a treatment layer with a thickness of 500 μm and a width of 100 mm. Corona discharge equipment was used, the mesh grid voltage was 10kV, the discharge distance was 1cm, and the processing speed was 800cm ² /min to obtain electroelectretized polytetrafluoroethylene binder particles (Fig. 2b).

2. Preparation of activated carbon electrode masterbatch

Electrode masterbatches were prepared using three-dimensional mixing equipment. Take 200g electroelectretized polytetrafluoroethylene, 100g carbon aerogel and 1700g activated carbon (D ₅₀ =50μm), place it in a three-dimensional mixing device, and pass it through a 100-mesh sieve after the number of rotations is 72 rpm and the treatment time is 30 minutes. , to obtain the activated carbon electrode masterbatch (Figure 3b).

3. Preparation of activated carbon electrode masterbatch diaphragm

Electrode masterbatch diaphragms were prepared by plunger extrusion and calendering. After taking 1000g of the electrode master material and compacting it: pressure 100.0MPa, compacting speed 50mm/min, compacting temperature 20°C, holding time 5s, the electrode master material blank was obtained. Place the pressed electrode master blank in a single plunger extruder to extrude the sample: extrusion speed 50mm/min, extrusion temperature 85°C, compression ratio (RR) 200, length-to-diameter ratio (L/D) 25. The cone angle (α) is 40°, and the electrode masterbatch sample strip with a diameter of 10mm is prepared. The electrode masterbatch sample was placed in a double-roll calender with an aspect ratio of 2.0, a calendering speed of 1m/min, and a roll temperature of 20°C to prepare an electrode masterbatch membrane with a thickness of 200μm and a width of 500mm (Figure 4b).

4. Activated carbon electrode masterbatch diaphragm deposition metal collector

The metal aluminum collector is deposited on the surface of the electrode mother material diaphragm by magnetron sputtering. Place the electrode master material diaphragm in the magnetron sputtering equipment, aluminum target (purity ≥ 99.99%), substrate temperature 200°C, argon gas pressure 4×10 ^-3 Torr, bias voltage -500V, deposition rate 50nm/ min, sputtering time 60min. Electrodes for supercapacitors with metal aluminum deposited on the activated carbon electrode masterbatch film were prepared (Fig. 5b).

5. Preparation of activated carbon electrode supercapacitor

Take activated carbon electrode masterbatch diaphragm to deposit metal aluminum as electrode for supercapacitor, size 200μm×10mm×27.5mm, Mitsubishi diaphragm paper (FPC3018) as electrode diaphragm, acetonitrile solution of tetraethylammonium tetrafluoroborate (1.0mol/L) As the electrolyte, it is assembled into a supercapacitor in a glove box with a water oxygen content of ≤10ppm. Under the conditions of 10.0A/g constant current and working voltage of 2.7V, the electrochemical data after 10,000 charge-discharge cycles are shown in Table 1.

Fig. 2 is a scanning electron micrograph before and after electric polarization of the polytetrafluoroethylene binder of the present invention (corresponding to Example 1). The results showed that before electroelectretization, the diameter of nano-sized PTFE particles was 20-30nm, and the degree of agglomeration between particles was relatively large (Fig. 2a); after electroelectretization, the diameter of PTFE particles increased slightly, and the particle size between particles The degree of agglomeration was reduced (Figure 2b). It shows that the electroelectretized polytetrafluoroethylene will increase the distance between molecular chains and reduce the agglomeration of polytetrafluoroethylene nanoparticles due to the repulsive force between the same kind of charges.

Fig. 3 is a scanning electron micrograph of an electrode masterbatch prepared with a polymer binder before and after electro-electretization of the present invention (corresponding to Example 1). The results show that the electrode masterbatch particles prepared by the non-electroelectretized polymer binder have obvious phase separation, and the larger activated carbon particles and the smaller particle size PTFE binder particles are not sufficiently uniformly dispersed. (Fig. 3a); in the electrode masterbatch that the polytetrafluoroethylene binder particle of electroelectretization prepares, the charged polytetrafluoroethylene binder particle of particle diameter is less, more evenly adsorbs on the bigger particle diameter Surface of activated carbon particles (Fig. 3b).

4 is a scanning electron micrograph of the electrode masterbatch of the present invention (corresponding to Example 1) directly calendering the diaphragm and the calendering and rolling diaphragm extruded by a plunger extruder. The results show that the PTFE fiberization degree of the electrode masterbatch directly calendered electrode masterbatch diaphragm is low, and the binding and bonding effect on the electrode active material particles is poor (Figure 4a); the electrode masterbatch plunger extrusion sample The calendered diaphragm has a high degree of fibrosis of the PTFE binder, which has a good effect on the binding and bonding of the electrode active material particles, and the contact between the particles is close (Figure 4b).

Fig. 5 is an optical photo before and after depositing a metal collector on the electrode masterbatch film of the present invention (corresponding to Example 1). The results show that before the metal is deposited, the surface of the electrode masterbatch diaphragm shows the black surface of activated carbon particles (Figure 5a); after the electrodeposition of metal aluminum, the surface of the electrode masterbatch diaphragm presents the silvery white of metallic aluminum, without obvious Phenomena such as cracks, delamination, and peeling indicate that the metal deposition layer is well bonded to the electrode master film (Figure 5b).

Fig. 6 is the cycle charge and discharge retention rate test curves of Example 1 and Comparative Example 1. The results show that the capacitance retention rate of the supercapacitor prepared in Example 1 is much better than that of the supercapacitor in Comparative Example 1.

Example 2

1. Electroelectrification of polypropylene electrode binder

The electroelectretization of polypropylene binder was carried out by thermal polarization method. Take 300 g of polypropylene binder particles with a molecular weight of 5 million and a particle size of 50 μm, and evenly spread them on the surface of the copper plate to form a treatment layer with a thickness of 1 mm and a width of 100 mm. The heat treatment temperature is 120° C., the polarization electric field intensity is 150 MV/m, and the polarization speed is 600 cm ² /min to obtain an electroelectretized polypropylene adhesive.

2. Preparation of positive electrode masterbatch for lithium ion battery

The electrode masterbatch was prepared by high-speed stirring equipment. Take 200g electroelectretized polypropylene, 100g Ketjen black and 1700g lithium iron phosphate (D ₅₀ =5 μm), place in a high-speed stirring device, the number of revolutions is 2500 rpm, and the treatment time is 3min, and pass through a 100-mesh sieve to obtain Lithium-ion battery cathode masterbatch.

3. Preparation of cathode masterbatch diaphragm for lithium ion battery

Electrode diaphragms were prepared by the plunger extrusion method. Take 1000g of electrode masterbatch compact: pressure 10.0MPa, compaction speed 20mm/min, holding time 10s, compaction temperature 60°C. Place the pressed electrode masterbatch in a double plunger extruder: extrusion speed 10mm/min, extrusion temperature 310°C, compression ratio (RR) 500, length-to-diameter ratio (L/D) 5, cone angle (α) 90°, to obtain a 2cm×5cm rectangular cathode masterbatch spline. The electrode masterbatch sample was placed in a 5-roller calender with an aspect ratio of 2.5, a calendering speed of 5m/min, and a roll temperature of 200°C to prepare a lithium-ion battery cathode masterbatch diaphragm with a thickness of 5mm and a width of 1000mm.

4. Lithium-ion battery cathode masterbatch diaphragm deposited aluminum collector

A metal aluminum collector is deposited on the surface of the electrode master material by an evaporation deposition method. Place the electrode masterbatch diaphragm in the evaporation equipment, silver target (purity ≥ 99.99%), substrate temperature 120 ° C, evaporation current 500A, deposition thickness of 5 μm silver collector, to obtain the masterbatch diaphragm deposited metal silver collector Electrodes for positive electrodes of lithium-ion batteries.

5. Preparation of Li-ion battery

Take the metal silver collector deposited on the masterbatch diaphragm as the electrode, the size is 200 μm × 10mm × 27.5mm, the Celgard (2400) diaphragm paper is the electrode diaphragm, the flake graphite electrode is the negative electrode, and the ethylene carbonate solution of lithium hexafluorophosphate (1.0mol/L) As the electrolyte, it is assembled into a supercapacitor in a glove box with a water oxygen content of ≤10ppm. Under the conditions of 10.0A/g constant current and working voltage of 3.7V, the electrochemical data after 300 charge and discharge are shown in Table 1.

Example 3

1. Electrostatic polarization of polyvinylidene fluoride binder

The polyvinylidene fluoride binder was electretized by high-voltage electrospinning. Take 300 g of polyvinylidene fluoride with a weight average molecular weight of 2 million and a particle size of 10 μm, and prepare an electrospinning solution with a concentration of 15 wt.% in N,N'-dimethylformamide. Under the conditions of a spinning voltage of 15kV, a spinning distance of 10cm, and a spinning speed of 2.0mL/h, an electretized polyvinylidene fluoride electrostatic spinning fiber binder was obtained.

2. Preparation of lithium ion capacitor negative electrode masterbatch

Anode masterbatches for lithium-ion capacitors were prepared using gravity-free mixing equipment. Take 200g electroelectretized polydidene fluoride, 100g spherical graphite and 1700g negative electrode material (hard carbon: lithium titanate mass ratio=0.8:1.0), place in gravity-free mixing equipment, the number of revolutions is 81 rpm, The filling factor is 0.6, and the processing time is 3 minutes to obtain the lithium ion capacitor negative electrode masterbatch.

3. Preparation of lithium-ion capacitor negative electrode masterbatch diaphragm

Electrode membranes were prepared by plunger extrusion and calendering. Take 1000g of electrode masterbatch compact: pressure 1.0MPa, compaction speed 10mm/min, holding time 7s, compaction temperature 120°C. Place the pressed electrode masterbatch in a single plunger extruder to extrude the sample: extrusion speed 100mm/min, extrusion temperature 30°C, compression ratio (RR) 50, length-to-diameter ratio (L/D) 50. With a cone angle (α) of 10°, an electrode masterbatch sample strip with a diameter of 10mm is prepared. The electrode masterbatch sample was placed in a three-roll calender with an aspect ratio of 3.0, a calendering speed of 10m/min, and a roll temperature of 60°C to prepare an electrode masterbatch diaphragm with a thickness of 150μm and a width of 600mm.

4. Lithium-ion capacitor negative electrode masterbatch diaphragm deposition metal copper

Metal copper is deposited on the surface of the collector of the electrode master material by the atomic layer deposition method. The electrode masterbatch diaphragm is placed in the atomic layer deposition equipment, bis(hexafluoroacetylacetonate) copper is the precursor, the deposition temperature is 120°C, the input power is 300W, the deposition rate is 0.1nm/cycle, and the deposition thickness is 2μm. An electrode for a lithium ion capacitor with metal copper deposited on a masterbatch film is prepared.

5. Preparation of lithium-ion capacitors

Take the metal copper collector deposited on the masterbatch diaphragm as the electrode, the size is 200μm×10mm×27.5mm, the Celgard (2325) separator paper is the electrode separator, the lithium iron phosphate electrode is the positive electrode, and the propylene carbonate solution of lithium hexafluorophosphate (1.0mol/L) As the electrolyte, it is assembled into a supercapacitor in a glove box with a water oxygen content of ≤10ppm. Under the condition of 10.0A/g constant current and working voltage of 3.2V, the electrochemical data after 1000 charge and discharge are shown in Table 1.

Comparative example 1

1. Preparation of activated carbon electrode masterbatch

The electrode masterbatch was prepared using a three-dimensional mixing device. Take 200g of polytetrafluoroethylene, 100g of carbon airgel and 1700g of activated carbon, put them in a three-dimensional mixing equipment, the number of revolutions is 72 revolutions/min, and the treatment time is 30 minutes to obtain the electrode masterbatch. The scanning electron micrograph of the prepared electrode masterbatch is shown in Figure 2a.

3. Preparation of activated carbon electrode masterbatch diaphragm

Take 1000g of electrode masterbatch and place it in a twin-roll calender: aspect ratio 2.0, calendering speed 1m/min, roll temperature 20°C, and prepare an electrode masterbatch diaphragm with a thickness of 200μm and a width of 500mm.

Comparative example 2

1. Preparation of positive electrode masterbatch for lithium ion battery

The electrode masterbatch was prepared by high-speed stirring equipment. Take 200g of polypropylene, 100g of Ketjen black and 1700g of lithium iron phosphate (D ₅₀ =5μm), place it in a high-speed stirring device, the number of revolutions is 2500 rpm, and the processing time is 3min, and pass through a 100-mesh sieve to obtain the lithium-ion battery positive electrode mother material.

2. Preparation of cathode masterbatch diaphragm for lithium ion battery

Electrode diaphragms were prepared by direct calendering of masterbatch. Take 1000g of electrode masterbatch and place it in a 5-roller calender with an aspect ratio of 2.5, a calendering speed of 5m/min, and a roll temperature of 200°C to prepare a lithium-ion battery cathode masterbatch diaphragm with a thickness of 5mm and a width of 1000mm.

3. Preparation of positive electrode for lithium ion battery

The positive electrode masterbatch diaphragm of the lithium ion battery was adhered to the metal silver collector with a thickness of 200 μm by conductive adhesive (Henkel EB102) to prepare the positive electrode.

4. Preparation of Li-ion battery

Take the positive electrode of the above-mentioned lithium ion battery, the size thickness is 5mm×20mm in diameter, the Celgard (2400) separator paper is used as the electrode separator, the flake graphite electrode is used as the negative electrode, and the ethylene carbonate solution (1.0mol/L) of lithium hexafluorophosphate is used as the electrolyte. ≤10ppm glove box assembled into a button-type lithium-ion battery. Under the conditions of charge and discharge rate of 1C and working voltage of 3.7V, the electrochemical data after 300 charges and discharges are shown in Table 1.

Comparative example 3

1. Preparation of lithium ion capacitor negative electrode masterbatch

Anode masterbatches for lithium-ion capacitors were prepared using gravity-free mixing equipment. Get 200g polydene fluoride, 100g spherical graphite and 1700g negative electrode material (hard carbon:lithium titanate mass ratio=0.8:1.0), place in a gravity-free mixing device, the number of revolutions is 81 revolutions/min, and the filling factor is 0.6. The time is 3 minutes, and the negative electrode masterbatch of lithium ion capacitor is obtained.

2. Preparation of lithium-ion capacitor negative electrode masterbatch diaphragm

Electrode diaphragms were prepared by direct calendering of masterbatch. Take 1000g of electrode masterbatch and place it in a three-roll calender with an aspect ratio of 3.0, a calendering speed of 10m/min, and a roll temperature of 60°C to prepare an electrode masterbatch diaphragm with a thickness of 150μm and a width of 600mm.

3. Preparation of Li-ion Capacitor Negative Electrode

The lithium-ion capacitor negative electrode masterbatch diaphragm was adhered to a metal copper collector with a thickness of 300 μm by conductive adhesive (Henkel EB102) to prepare a negative electrode for lithium-ion capacitors.

4. Preparation of lithium-ion capacitors

Take the negative electrode for lithium ion capacitor, the size is 200 μm × 10mm × 27.5mm, Celgard (2325) separator paper is the electrode separator, the lithium iron phosphate electrode is the positive electrode, and the propylene carbonate solution (1.0mol/L) of lithium hexafluorophosphate is the electrolyte solution. Supercapacitors were assembled in a glove box with an oxygen content of ≤10ppm. Under the condition of 10.0A/g constant current and working voltage of 3.2V, the electrochemical data after 1000 charge and discharge are shown in Table 1.

The electrochemical performance table of electrochemical energy storage device in the embodiment of table 1 and comparative example

As can be seen from Table 1, compared with the electrochemical data of Example 1 and Comparative Example 1, the results show that the energy density of Example 1 is lower due to reasons such as omitting the conductive adhesive, better fiberization of the binder, and thinning of the current collector. The energy density (~1.8 times) is higher than that of Comparative Example 1; due to the adoption of methods such as electretization of conductive agent and plunger extrusion processing, the binder has a high degree of fiberization and uniform distribution, making the contact between electrode active materials more efficient. Compact and strong, at the same time, the collector is directly compounded with the electrode active material as the base material through vapor deposition, thus resulting in a reduction in the internal resistance of the capacitor (~3.2 times), an increase in charge and discharge efficiency (~1.2 times) and a maximum power density Increased (~1.2-fold).

Compared with the electrochemical data of Example 2 and Comparative Example 3, the results show that the energy density of Example 2 is higher than that of Comparative Example 1 due to the omission of conductive adhesive, good fibrosis of the binder and thinning of the current collector. Density (~1.3 times); due to the use of conductive agent electretization, plunger extrusion processing and other methods, the binder has a high degree of fibrosis and uniform distribution, making the contact between the electrode active materials closer and firmer. The electrode is directly compounded with the electrode active material as the base material through vapor deposition, which leads to a decrease in the internal resistance of the capacitor (~1.9 times), an increase in charge and discharge efficiency (~1.2 times) and an increase in the maximum power density (~1.2 times).

Compared with the electrochemical data of Example 3 and Comparative Example 3, the results show that the energy density of Example 3 is higher than that of Comparative Example 3 due to reasons such as the omission of conductive adhesive, good binder fibrosis and thinning of the current collector. Density (~1.3 times); due to the use of conductive agent electretization, plunger extrusion processing and other methods, the binder has a high degree of fibrosis and uniform distribution, making the contact between the electrode active materials closer and firmer. The electrode is directly compounded with the electrode active material as the base material through vapor deposition, which leads to a decrease in the internal resistance of the capacitor (~1.9 times), an increase in charge and discharge efficiency (~1.2 times) and an increase in the maximum power density (~1.2 times).

The above are only specific embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A solvent-free preparation method of an electrode for an electrochemical energy storage device is characterized by comprising the following steps:

the method comprises the following specific steps:

(1) Polymer binder electro-electret

Placing the polymer binder powder in an electric polarization device, and performing electric polarization treatment on the polymer binder to obtain an electric polarization polymer binder;

(2) Preparation of electrode masterbatch

Placing the polymer binder subjected to electret polarization, the electrode active substance and the conductive agent in mixing equipment to be uniformly mixed to obtain electrode master batch;

(3) Preparation of electrode master batch membrane

Placing the electrode master batch into a compaction machine, placing the electrode master batch into a plunger type extruder after compacting, and extruding an electrode master batch sample strip; rolling the electrode master batch sample strip into an electrode master batch membrane with the thickness of 50 mu m-5 mm and the width of 100 mm-1000 mm in a rolling mill;

(4) Electrode prepared by depositing metal on electrode master batch membrane

And (3) placing the electrode master batch membrane in vapor deposition equipment, and depositing a layer of metal collector with the thickness of 10 nm-5 mu m on the surface of the electrode master batch at the deposition temperature of 80-200 ℃.

2. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: the polymer binder has the number average molecular weight of 200-1000 ten thousand and the grain size of 20 nm-50 microns.

3. A process for the solvent-free preparation of an electrode for an electrochemical energy storage device as claimed in claim 1, characterized in that: the polymer binder is at least one of polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride and polytetrafluoroethylene-hexafluoropropylene copolymer.

4. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: when the electro-electret treatment is carried out, one mode of electrostatic spinning, corona discharge, triboelectrification, thermal polarization and low-energy electron beam bombardment is adopted for treatment.

5. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: when electrostatic spinning electro-electret treatment is adopted, the spinning voltage is 15kV, the spinning distance is 10cm, and the spinning speed is 2.0mL/h;

when adopting corona discharge electro-electret treatment, the voltage of a net grid is 10kV, the discharge distance is 1cm, and the treatment speed is 800cm ² Min; when the thermal polarization and the electric polarization are adopted, the polymer adhesive is evenly paved on the surface of the copper plate to form a processing layer with the thickness of 1mm and the width of 100mm for heat treatment, the heat treatment temperature is 120 ℃, the intensity of the polarization electric field is 150MV/m, and the polarization speed is 600cm ² /min。

6. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: the mixing equipment is at least one of a high-speed stirrer, a V-shaped mixer, a gravity-free mixer, a three-dimensional mixer, a ball mill, an open mill, an internal mixer and an air flow mill; when mixing materials, the mixing temperature is 19-200 ℃, and the mixing time is 1-60 min.

7. A process for the solvent-free preparation of an electrode for an electrochemical energy storage device as claimed in claim 1, characterized in that: the electrode active substance is at least one of lithium salt, carbon-based porous material, graphite-based electrode material and metal oxide, and has a particle size D ₅₀ 5-50 μm; the conductive agent is at least one of carbon aerogel, conductive carbon black, crystalline flake graphite, carbon nano tubes, graphene and ball graphite, and the mass ratio of the polymer binder to the electrode active material to the conductive agent is 200.

8. A process for the solvent-free preparation of an electrode for an electrochemical energy storage device as claimed in claim 1, characterized in that: the green compact conditions are that the pressure is 1.0 MPa-10.0 MPa, the green compact speed is 5 mm/min-50 mm/min, the pressure maintaining time is 5 s-10 s, and the green compact temperature is 20-120 ℃;

the plunger type extruder is one of a vertical type, a horizontal type, a single column type, a double plunger type, a continuous type or an intermittent type, and the plunger type extrusion conditions are as follows: the extrusion speed is 10 mm/min-100 mm/min, the extrusion temperature is 30-310 ℃, the compression ratio RR is 50-500, the length-diameter ratio L/D is 5-50, the cone angle alpha is 10-90 degrees, and the extruded electrode master batch sample strip is one of a rod, a rectangle, a belt or a tube;

the calender is 2-5 rollers, the length-diameter ratio is 2.0-3.0, the calendering speed is 1-10 m/min, and the roller temperature is 20-200 ℃.

9. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: the vapor deposition equipment is one of magnetron sputtering equipment, evaporation deposition equipment, ion plating equipment, pulse deposition equipment and atomic layer deposition equipment; the metal collector is made of one or more of copper, aluminum, silver, gold and platinum.

10. A method of solventless preparation of an electrode for an electrochemical energy storage device as in claim 1, characterized by: when the metal aluminum collector is deposited by adopting a magnetron sputtering deposition mode, the purity of an aluminum target material is more than or equal to 99.99 percent, the temperature of a substrate is 200 ℃, and the argon pressure is 4 multiplied by 10 ^-3 Torr, bias voltage is-500V, deposition rate is 50nm/min, sputtering time is 60min;

when the metallic silver collector is deposited by adopting an evaporation deposition mode, the purity of a silver target material is more than or equal to 99.99 percent, the temperature of a base material is 120 ℃, the evaporation current is 500A, and the deposition thickness is 5 mu m;

when the metal copper collector is deposited by adopting an atomic layer deposition mode, bis (hexafluoroacetylacetone) copper is used as a precursor, the deposition temperature is 120 ℃, the input power is 300W, the deposition rate is 0.1 nm/cycle, and the deposition thickness is 2 mu m.

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