CN115121388A - A dry-process battery pole piece primer - Google Patents

Abstract

The invention relates to a dry-process battery pole piece primer, comprising: a laser drive unit, a light foil unwinding unit, a dry coating unit and a primer pole piece winding unit; the light foil unwinding unit is used for automatic foil unwinding. Roll out the light foil to be coated; the laser driving unit generates laser, ionizes the coating material powder in the dry coating unit, generates plasma charged particles, and is deposited on the light under the guidance of the magnetic field On the foil, a foil coated with a dry powder material is obtained; the coated foil is wound by a primer-coated pole piece winding unit to form a primer-coated pole piece.

Description

A dry-process battery pole piece primer

technical field

The invention relates to the technical field of material processing equipment, in particular to a dry-process battery pole piece primer.

Background technique

In recent years, due to the large-scale application of lithium-ion batteries, especially power batteries, higher requirements have been placed on the energy density, cycle performance, charge-discharge current density and safety performance of the battery. The improvement of the comprehensive performance of lithium batteries is very important. In lithium batteries, especially the low-conductivity lithium iron phosphate and silicon negative electrode systems, the positive and negative electrode sheets are coated with conductive carbon-based materials, which can significantly reduce the internal resistance of the battery, improve the cycle performance of the lithium battery, and prolong the effective life of the battery; gradually It has become an important modification method of lithium battery pole pieces.

The quality of the electrode primer directly affects the overall performance of the final battery. At present, the conductive carbon layer on the bottom of the pole piece mainly adopts the gravure coating process, in which a certain liquid solvent is used to prepare the conductive material into a suspension slurry, which is coated by gravure and then cured by an oven drying process. On the one hand, under the condition of ensuring better interfacial contact, the thinner the conductive carbon layer, the better the electrical conductivity, and the more conducive to the improvement of the energy density of the cell; therefore, an important development direction of the pole piece primer is to reduce the The thickness of the conductive carbon layer can improve the control accuracy of the coating thickness and ensure a high level of product consistency; on the other hand, in the wet coating process, pinholes, vertical stripes, shrinkage, Coating defects such as holes and orange peels affect the yield; finally, due to the inevitable drying process in the wet coating process, the size of the equipment is large, and the coating rate and production efficiency are limited. Therefore, the development of a high-speed dry-process pole piece primer will play an important role in improving the quality and production efficiency of pole piece primer products, and further improving the overall performance of lithium batteries.

SUMMARY OF THE INVENTION

The embodiment of the present invention provides a dry-process battery pole piece primer coater, which utilizes the effects of physical adsorption and plasma deposition, and realizes foil coating with dry powder as the coating material under the confinement and guidance of a magnetic field. The process does not contain liquid solvents, which avoids various problems in the wet coating process, not only optimizes and simplifies the structure of the pole piece primer, but also obtains coating foils with better consistency.

To this end, an embodiment of the present invention provides a dry-process battery pole piece primer coater, including: a laser drive unit, a light foil unwinding unit, a dry-process coating unit, and a primer pole piece winding unit;

The light foil unwinding unit performs automatic foil unwinding, and releases the light foil to be coated and sends it to the dry coating unit; the laser driving unit generates a laser to ionize the coating material powder in the dry coating unit , to generate plasma charged particles, which are deposited on the light foil under the guidance of the magnetic field to obtain a foil coated with dry powder material; the coated foil is wound by the bottom-coated pole piece winding unit to form Primed pole pieces.

Preferably, the dry coating unit includes: a laser incident window, a laser line focusing mirror, a powder circulating mold cavity, a plasma confinement guiding module and a plasma sputtering coating module;

The laser generated by the laser driving unit enters the dry coating unit through the laser incident window, is reflected by the laser line focusing mirror, and enters the powder circulating mold cavity through the entrance of the powder circulating mold cavity. The circulating mold cavity is focused on the focus of the laser line, and the powder of the coating material in the powder circulating mold cavity is ionized to form a plasma, which is diffused to the outside of the powder circulating mold cavity through the outlet of the powder circulating mold cavity. A directional plasma flow is formed under the guidance of the magnetic field of the plasma confinement guide module and deposited on the light foil delivered by the plasma sputter coating module.

Further preferably, the plasma confinement guide module includes a permanent magnet or an electromagnet;

The plasma sputter coating module includes: a coating back roller; the coating back roller is located behind the plasma confinement guide module, and the deposition area of the light foil conveyed on the coating back roller is aligned with the plasma Constrain the ejection direction of the plasma flow of the guiding module; the coating back rollers are arranged in one or more groups in parallel, and the number of groups of coating back rollers in the dry-process battery pole piece primer coater is based on a single set of coating back rollers The width of the roll and the width of the foil to be coated are set.

Further preferably, the coating material powder in the powder circulating mold cavity is sprayed into the powder supply pipeline, and the flowing powder layer flows with the gas in the powder circulating mold cavity;

On the one hand, the coating material powder is excited by laser to have adsorption activity, and on the other hand, plasma is formed by plasma ionization, and the coating on the optical foil is realized under the combined action of physical adsorption and plasma deposition.

Further preferably, the thickness of the coating on the primer pole piece is adjusted by adjusting the flow rate of the coating material powder, the power of the laser, the distance between the focus of the laser line and the light foil to be coated on the coating back roller, and the plasma. The magnetic field strength of the constraining guidance module can be adjusted.

Preferably, the dry coating unit is one or more groups;

A plurality of groups of the dry coating units are sequentially arranged in series for double-sided and/or multi-layer coating.

Preferably, the laser is a continuous laser or a pulsed laser;

When it is a pulsed laser, the repetition frequency of the pulsed laser is 1-1000000Hz; the energy of a single pulse is 1-100000mJ; and the pulse duration is 10 ^-6 -10 ^-15 seconds.

Preferably, the repetition frequency of the pulsed laser is 10-100000Hz; the energy of a single pulse is ^10-1000mJ ; and the pulse duration is ^10-9-10-15 seconds.

Preferably, the dry-process battery pole piece primer coater is used for the preparation of pole piece foils for primary batteries, secondary batteries and fuel cells;

Wherein, the secondary battery includes: liquid state, solid-liquid mixed or all-solid state lithium battery, sodium battery and lithium-sulfur battery.

Preferably, the coating material powder suitable for the dry-process battery pole piece primer includes: a mixture of one or more of ceramic powder, resin powder, solid electrolyte powder, and hydroxide powder ;

The coating material powder is also mixed with solid binder powder, and the solid binder powder accounts for 0-30 wt % of the total mass of the coating material powder.

In the dry process battery pole piece primer coating machine provided by the embodiment of the present invention, the foil is automatically unrolled through the light foil unwinding unit, and the light foil to be coated is released and sent to the dry process coating unit; the laser drive unit generates laser light, ionizes The coating material powder in the dry coating unit utilizes the effects of physical adsorption, plasma deposition and magnetic field guidance to realize the coating on the optical foil with the dry powder as the coating material, and obtain the material coated with the dry powder. The coated foil is wound by the primer-coated pole piece winding unit to form the primer-coated pole piece. The dry-process battery pole piece bottom coating machine proposed by the invention does not use liquid solvent in the process, avoids various problems existing in the wet coating process, not only optimizes and simplifies the structure of the coating machine, but also obtains better consistency. The coated foil has the advantages of simple process, uniform coating, high coating thickness precision and high coating production efficiency.

Description of drawings

The technical solutions of the embodiments of the present invention will be described in further detail below through the accompanying drawings and embodiments.

1 is a schematic structural diagram of a dry-process battery pole piece primer coater provided in an embodiment of the present invention;

2 is a schematic structural diagram of a dry coating unit provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of a coating principle provided by an embodiment of the present invention.

Detailed ways

The present invention will be further described below through the accompanying drawings and specific embodiments, but it should be understood that these embodiments are only used for more detailed description, and should not be construed as limiting the present invention in any form, that is, it is not intended to to limit the protection scope of the present invention.

The main structure of the dry-process battery pole piece primer proposed by the present invention is shown in Figure 1, including: a laser drive unit 1, a light foil unwinding unit 2, a dry-process coating unit 3 and a primer pole piece winding unit 4;

The light foil unwinding unit 2 performs automatic foil unwinding, releases the light foil to be coated, and sends it to the dry coating unit 3; the laser driving unit 1 generates a laser to ionize the coating material powder in the dry coating unit 3 body, and plasma charged particles are generated, which are deposited on the optical foil under the guidance of the magnetic field to obtain a foil coated with dry powder material. The coated foil is wound by the primer-coated pole piece winding unit 4 to form the primer-coated pole piece.

The above-mentioned light foil unwinding unit 2 and undercoating pole piece winding unit 4 are the same as the corresponding parts of the existing foil coating equipment, and will not be described here. The emphasis is on the laser drive unit 1 and the dry coating unit 3. In the present invention, the laser generated by the laser driving unit 1 interacts with the coating material powder in the dry coating unit 3, so that the coating material powder is excited by the laser to have adsorption activity on the one hand, and plasma ionization occurs on the other hand. Plasma is formed, and a directional plasma flow is formed under the guidance of the magnetic field, and the coating on the optical foil is realized under the combined action of physical adsorption, plasma deposition and guidance of the magnetic field.

The inside of the laser driving unit 1 may specifically include a laser generating module, a laser transmission module and a laser focusing module. The laser transmission module may specifically include optical components such as optical fibers, coated mirrors, and corresponding vacuum pipelines.

The laser emitted by the laser driving unit 1 is a continuous laser or a pulsed laser, preferably a pulsed laser. The repetition frequency of the pulsed laser is 1-1000000 Hz; preferably 10-100000 Hz. The single pulse energy of the pulsed laser is 1-100000 mJ; preferably 10-10000 mJ; more preferably 10-1000 mJ. In this embodiment, the pulse width of the pulsed laser can be in the order of microseconds, nanoseconds, picoseconds and femtoseconds, and the pulse duration is 10 ^-6 -10 ^-15 seconds, preferably 10 ^-9 -10 ^-15 seconds.

The specific structure of the dry coating unit 3 is shown in FIG. 2 , including: a laser incident window 31 , a laser line focusing mirror 32 , a powder circulating cavity 33 , a plasma confinement guide module 34 and a plasma sputter coating module.

The laser light generated by the laser driving unit 1 (shown by the solid arrow on the left in FIG. 2 ) enters the dry coating unit 3 through the laser incident window 31 , is reflected by the laser line focusing mirror 32 , and enters the powder through the powder circulation cavity entrance 331 The circulating mold cavity 33 is focused on the laser line focus in the powder circulating mold cavity 33 (the dotted line at the intersection of the solid arrow and the oblique arrow in FIG. 2 ) to ionize the coating material powder in the powder circulating mold cavity 33, Plasma is formed and radiated to the outside of the powder circulating mold cavity through the outlet 332 of the powder circulating mold cavity, and a directional plasma flow deposition is formed under the guidance of the magnetic field of the permanent magnet or electromagnet included in the plasma confinement guide module 34 On the light foil delivered by the plasma sputter coating module.

The plasma sputter coating module includes a coating back roll 35 . Wherein, the coating back roll 35 is located behind the plasma confinement guide module, and the deposition area of the light foil conveyed on the coating back roll 35 is aligned with the exit direction of the plasma stream of the plasma confinement guide module 34 .

Optionally, the plasma sputtering coating module may further include a laser baffle (not shown in the figure) to shield the region other than the deposition region in the plasma divergent region. In this way, the dispersion of the plasma is selectively blocked, so that the coating material powder is deposited on the light foil conveyed by the coating back roller 35 .

In the powder circulating mold cavity 33, the coating material powder is sprayed into the powder supply pipe 333 of the powder circulating mold cavity 33, and a flowing powder layer is formed with the gas flow in the powder circulating mold cavity 33; the coating material powder In the area with strong laser electric field intensity (mainly at the focus of laser line and its vicinity), the powder will be ionized by strong electric field to form plasma, and the plasma will diverge into a plasma halo region with the focus of laser line as the cylindrical symmetry axis; The halo region contains a large number of active particles such as electrons, charged ions, atoms in excited states, molecules and free radicals, and also contains a large number of particles in a molten state; the above particles radiate outward in a cylindrical cone-shaped spatial distribution, and then pass through the magnetic field. The electromagnetic force guides and confines the motion of the particles above, which are deposited on the light foil. That is to say, the coating is mainly formed by deposition; at the same time, in the region where the laser intensity is weak in the powder circulation die cavity 33, the laser will also excite the dry powder to make it have adsorption activity, so that it can be adsorbed on the surface of the foil.

In the plasma deposition process, the coating material powder is ionized to form a plasma, and the charged particles in the plasma then excite the thin layer (molecular/atomic layer) on the surface of the optical foil. The charged ions in the non-equilibrium plasma can have a plasma temperature of the order of keV, and have sufficient energy to promote the breaking of chemical bonds in the thin layer on the surface of the foil and reduce the local system energy by forming new bonds, and the deposition process also includes The formation of free radicals, double bonds, etc., thus enables the deposited coating material powder to be tightly bound to the surface of the foil without falling off.

The thickness of the coating on the primer pole piece can be adjusted to the plasma confinement guiding module by adjusting the flow rate of the coating material powder, the power of the laser, the distance between the focus of the laser line and the light foil to be coated on the coating back roller. The magnetic field strength can be adjusted. Through the dry-process battery pole piece primer coating machine of the present invention, the coating thickness can be adjusted within the range of 0.05-5um, and the controllable adjustment precision of the coating thickness can reach below 0.05um.

In a specific embodiment, the effective coating base film width of each dry-process coating unit 3 is 100mm-2000mm; the effective coating width of the dry-process battery pole piece primer coater can be determined by the direction perpendicular to the paper surface in FIG. 2 . A plurality of dry coating units 3 are arranged in gaps to form a group of dry coating units to control the width of single-layer coating.

The coating of the coating area on the optical foil corresponding to the adjacent dry coating units 3 is the result of the superposition of the adjacent dry coating units 3, so the The spacing adjustment can adjust the uniformity of the functional coating in the width direction of the foil; in order to obtain a uniform and stable dry coating, the linear speed of the base film at the coating back roll should match the repetition frequency generated by the laser drive unit; Within a certain range, driving lasers with higher repetition frequencies are more beneficial to the uniformity of the coating and the ability of high-speed coating.

In addition, in the direction of movement of the foil, multiple groups of dry coating units can be arranged in series according to requirements, so as to conveniently realize multi-layer coating at one time. Specifically, by arranging multiple sets of laser driving units and multiple sets of dry coating units in series, the present invention can realize the one-time coating of the same or different materials on single-sided multi-layer, double-sided single-layer or double-sided multi-layer. The number of dry coating units 3 can be 1 group as shown in Figure 2, or can be multiple groups connected in series, for example, the number can be arbitrarily selected between 1-100, preferably 1-10 groups, more preferably 1- 5 sets. In practical applications, a certain number of dry-process coating units can be connected in series as required. FIG. 3 is a schematic diagram of the coating working principle of the dry-process battery pole piece primer coater according to the embodiment of the present invention. Here, two dry coating units 3 placed in series are shown as an example.

The dry-process battery pole piece primer provided by the present invention is used for the preparation of foils for primary batteries, secondary batteries and fuel cells; wherein the secondary batteries may specifically include: liquid, solid-liquid mixed or all-solid lithium batteries, sodium batteries and lithium-sulfur batteries.

The coating material powder suitable for the dry-process battery pole piece primer of the present invention includes, but is not limited to, one or more of ceramic powder, resin powder, solid electrolyte powder, and hydroxide powder. mix. In addition, solid binder powder may also be mixed with the coating material powder, and the solid binder powder accounts for 0-30 wt % of the total mass of the coating material powder.

The light foil suitable for the dry-process battery pole piece primer of the present invention includes, but is not limited to, copper foil and aluminum foil.

In the dry process battery pole piece primer coating machine provided by the embodiment of the present invention, the foil is automatically unrolled through the light foil unwinding unit, and the light foil to be coated is released and sent to the dry process coating unit; the laser drive unit generates laser light, ionizes The coating material powder in the dry coating unit produces plasma charged particles, which are deposited on the foil under the guidance of a magnetic field. The invention utilizes the functions of physical adsorption, plasma deposition and magnetic field guidance to realize the coating on the light foil with the dry powder as the coating material, so as to obtain the foil coated with the dry powder material; the coated foil is composed of The undercoating pole piece winding unit is wound to form the undercoating pole piece. The dry-process battery pole piece bottom coating machine proposed by the invention does not use liquid solvent in the process, avoids various problems existing in the wet coating process, not only optimizes and simplifies the structure of the coating machine, but also obtains better consistency. The coated foil has the advantages of simple process, uniform coating, high coating thickness precision and high coating production efficiency.

The specific embodiments described above further describe the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. The dry-method battery pole piece base coating machine is characterized by comprising the following steps: the device comprises a laser driving unit, an optical foil unreeling unit, a dry coating unit and a bottom coating pole piece reeling unit;

the optical foil unreeling unit automatically unreels the foil, and emits the optical foil to be coated to be sent to the dry coating unit; the laser driving unit generates laser, the coating material powder in the dry coating unit is ionized to generate plasma charged particles, and the plasma charged particles are deposited on the optical foil under the guiding action of a magnetic field to obtain the foil coated with the dry powder material; and winding the coated foil by a first-coating pole piece winding unit to form a first-coating pole piece.

2. The dry process battery pole piece priming machine of claim 1, wherein the dry process coating unit comprises: the device comprises a laser incidence window, a laser line focusing mirror, a powder circulating die cavity, a plasma confinement guide module and a plasma sputtering coating module;

the laser driving unit generates laser which enters the dry coating unit through the laser incidence window, is reflected by the laser line focusing mirror, enters the powder circulating die cavity through the powder circulating die cavity inlet, is focused at the laser line focus in the powder circulating die cavity, ionizes coating material powder in the powder circulating die cavity to form plasma, is emitted to the outside of the powder circulating die cavity through the powder circulating die cavity outlet, forms directional plasma flow under the guidance of the magnetic field of the plasma confinement guide module, and deposits on the optical foil conveyed by the plasma sputtering coating module.

3. The dry process battery pole piece priming machine according to claim 2,

the plasma confinement guiding module comprises a permanent magnet or an electromagnet;

the plasma sputter coating module includes: coating a back roll; the coating back roll is positioned behind the plasma confinement and guide module, and the deposition area of the optical foil conveyed on the coating back roll is aligned with the emission direction of the plasma flow of the plasma confinement and guide module; the coating back rollers are arranged in parallel in one group or multiple groups, and the number of the groups of the coating back rollers in the dry-method battery pole piece bottom coating machine is set according to the width of the single group of the coating back rollers and the width of the optical foil to be coated.

4. The dry-process battery pole piece primer coating machine according to claim 2, wherein coating material powder in the powder circulation mold cavity is sprayed from a powder supply pipeline, and a flowing powder layer flows along with gas in the powder circulation mold cavity;

the coating material powder is excited by laser to have adsorption activity, and plasma is formed through plasma ionization, so that coating on the optical foil is realized under the combined action of physical adsorption and plasma deposition.

5. The dry-process battery pole piece primer coating machine according to claim 4, wherein the thickness of the coating on the primer coating pole piece is adjusted by adjusting the flow rate of the powder injection of the coating material, the power of the laser, the distance between the focal point of the laser line and the optical foil to be coated on the coating back roll and the magnetic field strength of the plasma confinement guide module.

6. The dry process battery pole piece primer coating machine according to claim 1, wherein the dry process coating units are 1 or more groups;

and multiple groups of dry coating units are sequentially arranged in series for double-sided and/or multilayer coating.

7. The dry process battery pole piece primer coating machine according to claim 1, wherein the laser is a continuous laser or a pulsed laser;

when the laser is pulse laser, the repetition frequency of the pulse laser is 1-1000000 Hz; the single pulse energy is 1-100000 mJ; pulse duration of 10 ^-6 -10 ^-15 And second.

8. The dry process battery pole piece priming machine according to claim 1,

the repetition frequency of the pulse laser is 10-100000 Hz; the single pulse energy is 10-1000 mJ; pulse duration of 10 ^-9 -10 ^-15 And second.

9. The dry-process battery pole piece primer coating machine according to claim 1, wherein the dry-process battery pole piece primer coating machine is used for preparing pole piece foils of primary batteries, secondary batteries and fuel batteries;

wherein the secondary battery includes: liquid, solid-liquid mixed or all solid lithium batteries, sodium batteries and lithium sulfur batteries.

10. The dry process battery pole piece primer coating machine according to claim 1, wherein the coating material powder suitable for the dry process battery pole piece primer coating machine comprises: mixing one or more of ceramic powder, resin powder, solid electrolyte powder and hydroxide powder;

the coating material powder is also mixed with solid binder powder, and the solid binder powder accounts for 0-30 wt% of the total mass of the coating material powder.

Images