CN116014363A - A kind of preparation method of composite current collecting and separating layer - Google Patents

Abstract

The invention provides a preparation method of a composite current collecting isolation layer. In the preparation method, a porous electrode current collector is placed on a plurality of stainless steel wires, and an arch part is formed on the porous electrode current collector by heating and pressurizing treatment, wherein the section of the arch part is in an arch shape with one concave surface and one convex surface. The porous electrode current collector and the diaphragm are combined into a whole, and a flow channel for electrolyte is formed between the concave part of the arch part of the porous electrode current collector and the diaphragm, so that the electrolyte can enter the electrode plate rapidly through the flow channel, and the electrolyte in the flow channel is injected into the electrode material layer through the through holes of the porous electrode current collector, so that the electrode material layer in the electrode plate can be infiltrated rapidly. In the composite current collecting isolation layer, burrs at the edges of the porous electrode current collector are flattened, and the edges of the separator are subjected to edge wrapping composite treatment on the porous electrode current collector, so that short circuit of the battery caused by contact of the burrs at the edges of the porous electrode current collector can be effectively prevented.

Description

A kind of preparation method of composite current collecting and separating layer

technical field

The invention relates to the field of lithium slurry batteries, in particular to a preparation method of a composite current collecting and separating layer.

Background technique

Lithium slurry battery is a new type of lithium battery. Lithium slurry battery has a three-dimensional porous cell structure, and the electrode material layer contains a certain proportion of non-adhesive and fixed conductive particles, which can form a dynamic conductive network in the electrolyte to avoid the traditional lithium-ion battery electrode material from falling off or loosening. problems such as battery capacity decline and cycle life attenuation. Large-capacity lithium slurry battery has the function of liquid injection and discharge, and its electrode thickness is 5 to 10 times that of traditional lithium-ion batteries. Therefore, if more channels are provided for electrolyte to enter during liquid injection and discharge, it will greatly improve the efficiency of liquid injection and discharge. The efficiency is conducive to the infiltration of the liquid inside the electrode; and because of the thick electrode structure, more cooling and exhaust channels are provided inside the cell to prevent bubbles and other residues on the surface of the electrode sheet from affecting the normal charge and discharge reaction of the battery.

Contents of the invention

In view of the above existing problems, the present invention provides a method for preparing a composite current collecting and separating layer. In this preparation method, the porous electrode current collector is placed on a plurality of stainless steel wires, and an arched part is formed on the porous electrode current collector by means of heat and pressure treatment. The cross section of the arched part is an arch with one side concave and one side convex shape. Combining the porous electrode current collector with the diaphragm, a flow channel for the electrolyte is formed between the concave part of the arched part of the porous electrode collector and the diaphragm, which is conducive to the rapid entry of the electrolyte into the electrode sheet through the flow channel. The electrolyte solution in the flow channel is injected into the electrode material layer through the through holes of the porous electrode collector, so that the electrode material layer in the electrode sheet can be quickly wetted. In the composite current collector separation layer, the burrs on the edge of the porous electrode collector are flattened and the edge of the separator wraps the porous electrode collector, which can effectively prevent the short circuit of the battery caused by the contact of the burr on the edge of the porous electrode collector.

The technical scheme provided by the invention is as follows:

According to the present invention there is provided a method for preparing a composite current collecting and isolating layer, the method comprising the following steps:

(a) laying a plurality of stainless steel wires under the porous electrode current collector, at least some of the ends of the stainless steel wires extend beyond the edge of the porous electrode current collector;

(b) Use a press to heat and press the porous electrode current collector, and the porous electrode current collector is bent and deformed at the part in contact with the stainless steel wire, thereby forming an arched part with one side concave and one side convex on the porous electrode current collector ;

(c) On the concave side of the arched part of the porous electrode current collector, the planar part of the porous electrode current collector is combined with the diaphragm, and a flow channel is formed between the concave part of the arched part of the porous electrode current collector and the diaphragm, At the same time, the edge of the diaphragm is subjected to edge-wrapping composite treatment on the porous electrode current collector.

The porous electrode current collector can be a porous positive current collector, the porous positive current collector can be an electronically conductive layer with a through-hole structure with a thickness of 1 μm to 2000 μm, the pore diameter of the porous positive current collector can be 0.01 μm to 2000 μm, and the porosity of the through holes can be 10% to 90%. The porous positive current collector can be a conductive metal layer, and the conductive metal layer can be a metal mesh or a wire woven mesh; or, the conductive metal layer can be a foamed metal mesh with a through-hole structure; or, the conductive metal layer can be a porous metal plate or porous metal foil. The material of the conductive metal layer is preferably aluminum.

The porous electrode current collector can be a porous negative electrode current collector, and the porous negative electrode current collector can be an electronically conductive layer with a through-hole structure with a thickness of 1 μm to 2000 μm. The pore diameter of the porous negative electrode current collector can be 0.01 μm to 2000 μm. 10% to 90%. The porous negative electrode current collector can be a conductive metal layer, and the conductive metal layer can be a metal mesh or a wire braided mesh; or, the conductive metal layer can be a foamed metal mesh with a through-hole structure; or, the conductive metal layer can be a porous metal plate or porous metal foil. The material of the conductive metal layer is preferably copper.

The material of the diaphragm can be an electronically non-conductive porous polymer material; or, the material of the diaphragm can be a porous material composed of an electronically non-conductive inorganic non-metallic material and an organic polymer; or, the material of the diaphragm can be an electronically non-conductive polymer A gel polymer electrolyte composite material composed of a three-part composite of a matrix, a liquid organic plasticizer, and a lithium salt; or, the material of the separator can be in the pores of an electronically non-conductive porous polymer material or in an inorganic non-metallic material and The pores of the organic polymer composite porous material are impregnated with an ion-conducting electrolyte or a polymer colloid material, and the like.

Stainless steel wire can be placed directly under the porous electrode current collector. Alternatively, the stainless steel wire can be first laid in a mold for fixing the stainless steel wire, and then the porous electrode current collector is placed on the stainless steel wire. The mold used to fix the stainless steel wire can be, for example, a block mold with grooves, and the stainless steel wire can be stably placed in the groove. The arrangement of multiple stainless steel wires can be parallel, cross, radial, etc. Preferably, a plurality of stainless steel wires are intersected to form cross-connected channels on the porous electrode current collector, which is more conducive to the rapid flow of the electrolyte to the entire plane of the electrode material layer. In addition, stainless steel wires of different diameters can also be provided, for example, a main channel with a larger diameter and a branch channel with a smaller diameter are provided, or a large flow channel with a larger diameter is provided along the length direction of the pole piece. runner. In addition, the shape of the stainless steel wire can be wavy, Z-shaped, spiral, etc. The layout of the stainless steel wires can be flexibly set according to the needs, and the number of stainless steel wires can be increased or decreased according to the size of the pole piece, so that a flow channel for the flow of the electrolyte can be formed conveniently and flexibly in the battery cell. The ends of at least some of the stainless steel wires protrude from the edge of the porous electrode collector, so that after the plurality of electrode sheets are stacked into a battery core, a hole for the electrolyte to enter the battery is formed at the edge of the porous electrode collector. Arched opening inside the core.

Since the hardness of the stainless steel material is higher than that of aluminum or copper, when the stainless steel wire is stamped with a porous aluminum mesh (porous positive electrode current collector) or with a porous copper mesh (porous negative electrode current collector) by a press, the porous aluminum The mesh and perforated copper mesh form an arched portion such as a semicircle. The diameter of the stainless steel wire can be 0.5-5 mm, and the size of the arch can be controlled by controlling the diameter of the stainless steel wire. The heating temperature may be 50-200° C., and the pressing pressure may be 2-20 MPa. By controlling the heating temperature, the deformation of the porous electrode current collector can be facilitated, and the process of heating the composite separator can be realized while pressurizing.

The method of compounding the planar part of the porous electrode current collector and the diaphragm includes bonding or planar thermocompression compounding. Said, steps (b) and steps (c) can be completed in one step at the same time except for the hemming. Specifically, on the concave side of the arched portion of the porous electrode current collector, the portion of the porous electrode current collector that does not form the arched portion is connected to the separator, while the portion of the porous electrode current collector that forms the arched portion is not Connected with the diaphragm, a hollow flow channel is formed between the concave portion of the arched portion of the porous electrode collector and the diaphragm, and the cross-sectional shape of the flow channel may be, for example, a semicircle. By compounding and fixing the diaphragm and the edge plane part of the arched portion of the porous current collector, the shape of the arched portion of the porous current collector can be better maintained.

During the cutting and forming process of porous electrode current collectors, burrs perpendicular to the current collector plane often appear on the edges. When the burr is in direct contact with the separator, it is easy to pierce the separator and then contact the electrode material or current collector on the other side, thereby causing an internal short circuit of the battery. In the present invention, when the press is used to press the flow channel on the porous electrode collector, the burrs perpendicular to the plane of the collector can be flattened at the same time. In addition, the size of the diaphragm is slightly larger than the size of the porous electrode collector, so that the The edge extends beyond the edge of the porous electrode current collector, securing the edge of the separator over the edge of the porous electrode current collector. This method of flattening and fixing the coating (that is, edge-wrapping composite treatment) reduces the risk of burrs piercing the separator, especially when the coating is fixed by adhesive, which greatly improves the safety of the battery.

The preparation method of the present invention can be used to prepare the positive electrode composite current collecting and separating layer and the negative electrode composite current collecting and separating layer. In the positive electrode composite current collector separation layer, the porous electrode current collector is a porous positive electrode current collector such as aluminum mesh; in the negative electrode composite current collector separation layer, the porous electrode current collector is a porous negative electrode current collector such as copper mesh.

The positive electrode composite current collecting and separating layer and the negative electrode composite current collecting and separating layer can be used in batteries of lithium slurry batteries. In the battery cell of the lithium slurry battery, the diaphragm of the positive electrode composite current collecting and separating layer is placed opposite to the diaphragm of the negative electrode composite current collecting and separating layer, and the two layers of diaphragms are adjacent to each other. The outer side of the porous positive electrode current collector of the positive electrode composite current collection and separation layer is provided with a porous positive electrode material layer, and the outer side of the porous negative electrode current collector of the negative electrode composite current collection separation layer is provided with a porous negative electrode material layer. Another positive electrode composite current collector separation layer is set outside the porous positive electrode material layer, wherein the porous positive electrode current collector of the positive electrode composite current collector separation layer is adjacent to the porous positive electrode material layer; another negative electrode composite current collector is set outside the porous negative electrode material layer A current separation layer, wherein the porous negative electrode current collector of the negative electrode composite current collector separation layer is adjacent to the porous negative electrode material layer. In this manner, cells are stacked to form a lithium slurry battery. The porous positive electrode material layer and the porous negative electrode material layer can be in the form of powder, block or slurry, etc., because in the lithium slurry battery, after the electrolyte is injected, the porous positive electrode material layer and the porous negative electrode material layer are under the condition of external force Certain deformation can occur, therefore, when the porous positive electrode material layer is adjacent to the porous positive electrode current collector of the positive electrode composite current collecting and separating layer or when the porous negative electrode material layer is adjacent to the porous negative electrode collecting body of the negative electrode composite current collecting and separating layer, it does not The arched portion on the porous positive electrode current collector and the arched portion on the porous negative electrode current collector will be completely flattened, but the channel shape of the arched portion is maintained through the local deformation of the porous positive electrode material layer and the porous negative electrode material layer, thereby Flow channels for electrolyte flow are reserved in the cell.

In the aneroid cell, the stacking porosity of the non-adhesive and fixed positive electrode active conductive particles in the porous positive electrode material layer and/or the non-bonded and fixed negative electrode lithium storage conductive particles in the porous negative electrode material layer can be greater than 5% and Less than 60%. In the case of immersion in the electrolyte, the non-adhesive and fixed positive electrode active conductive particles and/or the non-bonded and fixed negative electrode lithium storage conductive particles can move in the electrolyte and form positive electrode slurry and/or negative electrode slurry respectively. The mass ratio of positive electrode active conductive particles to positive electrode slurry can be 10% to 90%, preferably 15% to 80%, and the mass ratio of negative electrode lithium storage conductive particles to negative electrode slurry can be 10% to 90%, preferably 15% to 80%. The average particle size of positive electrode active conductive particles can be 0.05 μm to 500 μm, and the mass ratio of positive electrode active material to conductive agent can be 20 to 98:80 to 2; the average particle size of negative electrode lithium storage conductive particles can be 0.05 μm to 500 μm, and the negative electrode storage The mass ratio of the lithium material to the conductive agent may be 20-98:80-2.

In the electric core of the lithium slurry battery, under the situation that the composite current collecting and separating layer according to the present invention is set, when the electrolyte is injected into the battery, the electrolyte will flow from the arched opening formed by the composite current collecting and separating layer on the surface of the electric core. Quickly enter the flow channel of the composite current collecting and separating layer, and then enter the porous electrode material layer through the porous electrode current collector of the composite collecting and separating layer, and quickly infiltrate the entire porous electrode material layer to form electrode slurry.

The advantages of the present invention are:

1) A flow channel for the electrolyte is formed between the concave part of the arched part of the porous electrode collector and the diaphragm, which is conducive to the rapid infiltration of the electrolyte inside the electrode sheet; the channel can also be used for heat dissipation during the use of the cell Exhaust to prevent bubbles and other residues on the surface of the electrode sheet from affecting the normal charge and discharge reaction of the battery;

2) In the composite current collector isolation layer, the edge of the diaphragm wraps the porous electrode collector, which can effectively prevent the short circuit of the battery caused by the burr contact on the edge of the porous electrode collector;

3) In the present invention, the arrangement of the stainless steel wires can be flexibly set according to the needs, and the number of stainless steel wires can be increased or decreased according to the size of the pole pieces, so as to conveniently and flexibly form a flow channel in the battery cell through which the electrolyte can circulate.

Description of drawings

Fig. 1 (a)-1 (d) is the schematic diagram according to the stainless steel wire arrangement in the preparation method of the present invention;

Fig. 2 (a)-2 (d) is the schematic diagram according to the preparation method of composite collector isolation layer of the present invention;

Fig. 3 is an electric core prepared according to the preparation method of the present invention.

List of reference signs:

1, 1a, 1b - stainless steel wire

2——Porous electrode current collector

2a——arched part

2b - Flow channel

3——Positive composite current collecting and separating layer

4——Negative compound current collecting and separating layer

5——Porous cathode material layer

6——Porous negative electrode material layer

7 - Diaphragm

Detailed ways

The present invention will be further described through embodiments below in conjunction with the accompanying drawings.

1(a)-1(d) are schematic diagrams of the arrangement of stainless steel wires in the preparation method according to the present invention. In the embodiment shown in Figure 1 (a), two groups of stainless steel wires 1 are arranged in parallel respectively, and the two groups of stainless steel wires 1 are mutually intersected again; In the embodiment shown in Figure 1 (b), multiple Stainless steel wire 1 is arranged in the mode that radiates outward along the center; In the embodiment shown in Fig. 1 (c), a plurality of stainless steel wires 1 are irregularly crossed; In the direction along the length of the pole piece, the stainless steel wire 1a with a larger diameter is set, and the stainless steel wire 1b with a smaller diameter is set along the direction along the width of the pole piece, so that even in the direction where the pole piece is longer Rapid liquid injection can also be realized on the top.

2(a)-2(d) are schematic diagrams of the preparation method of the composite current collecting and separating layer according to the present invention. First, as shown in Figure 2(a), the stainless steel wire 1 is laid, and the way of laying can be designed according to actual needs; then, as shown in Figure 2(b), the porous electrode current collector 2 is placed on the stainless steel wire 1 Above, at least part of the stainless steel wire 1 protrudes outward from the edge of the porous electrode current collector 2 . Use a press to heat and press the porous electrode current collector 2, the pressure can be 5MPa, and the temperature can be 120°C, so that the porous electrode current collector 2 is bent and deformed at the position in contact with the stainless steel wire 1 to form a coated stainless steel wire 1 The arched portion; as shown in Figure 2 (c), on the porous electrode current collector 2 after pressing, generate one side concave, one side convex arched portion 2a, the inner diameter of the arched portion 2a is the same as the outer diameter of the stainless steel wire Roughly the same; finally, as shown in Figure 2(d), on the concave side of the arched part 2a of the porous electrode current collector 2, the planar part of the porous electrode current collector 2 is bonded to the separator 7, and the porous electrode current collector A flow channel 2b for electrolyte circulation is formed between the recessed part of the arched part 2a of the fluid 2 and the diaphragm 7, and the edge of the diaphragm 7 performs edge wrapping composite treatment on the porous electrode current collector 2.

Fig. 3 is an electric core prepared according to the preparation method of the present invention. According to the preparation method of the composite current collecting and separating layer of the present invention, the positive electrode composite current collecting and separating layer 3 and the negative electrode composite current collecting and separating layer 4 are prepared. In the positive electrode composite current collecting and separating layer 3 , the porous positive electrode current collector is an aluminum mesh, and in the negative electrode composite collecting and separating layer 4 , the porous negative electrode current collector is a copper mesh. When preparing the electric core, a porous positive electrode material layer 5 is arranged between the two positive electrode composite current collector separation layers 3, and the convex side of the arched part of the porous positive electrode current collector of the positive electrode composite current collector separation layer 3 and the porous positive electrode material layer 5 Adjacent, a porous negative electrode material layer 6 is set between the two negative electrode composite current collector separation layers 4, and the convex side of the arched part of the porous negative electrode current collector of the negative electrode composite current collector separation layer 4 is adjacent to the porous negative electrode material layer 6, and the positive electrode composite The diaphragm of the current collecting and separating layer 3 is adjacent to the diaphragm of the negative electrode compound current collecting and separating layer 4, so as to be stacked to form an electric core.

When the electrolyte is injected into the battery, on the surface of the battery cell, the electrolyte enters the flow channel 2b of the composite collector separation layer through the arched opening formed by the edge of the porous electrode collector, and the electrolyte in the flow channel 2b can be Wetting the separator and wetting the porous electrode material layer through the porous electrode current collector, so as to achieve the purpose of rapid wetting of the entire battery cell.

The specific embodiments of the present invention are not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (8)

1. A preparation method of a composite current collecting and separating layer, characterized in that, the preparation method comprises the steps of: (a) laying a plurality of stainless steel wires under the porous electrode current collector, at least the ends of some stainless steel wires extend beyond The edge of the porous electrode current collector; (b) heat and pressurize the porous electrode current collector with a press, and the porous electrode current collector is bent and deformed at the part in contact with the stainless steel wire, so that A bent portion with one side concave and one side convex is formed on the porous electrode current collector; (c) on the concave side of the bent portion of the porous electrode current collector, the planar part of the porous electrode current collector and the diaphragm Composite, a flow channel is formed between the recessed part of the bent part of the porous electrode collector and the separator, and the edge of the separator performs edge-wrapping composite treatment on the porous electrode collector. 2. The preparation method according to claim 1, wherein the porous electrode current collector is a porous positive electrode current collector, and the porous positive electrode current collector is an electronically conductive layer having a through-hole structure with a thickness of 1 μm to 2000 μm, the The pore diameter of the porous positive current collector is 0.01 μm to 2000 μm, and the porosity of the through holes can be 10% to 90%. The porous positive current collector is a conductive metal layer, and the conductive metal layer is a metal mesh or a wire woven mesh; or , the conductive metal layer is a foamed metal mesh with a through-hole structure; or, the conductive metal layer is a porous metal plate or a porous metal foil, and the material of the conductive metal layer is aluminum. 3. The preparation method according to claim 1, wherein the porous electrode current collector is a porous negative electrode current collector, and the porous negative electrode current collector is an electronically conductive layer having a through-hole structure with a thickness of 1 μm to 2000 μm, the The pore diameter of the porous negative electrode current collector is 0.01 μm to 2000 μm, and the porosity of the through holes can be 10% to 90%. The porous negative electrode current collector is a conductive metal layer, and the conductive metal layer is a metal mesh or a wire woven mesh; or , the conductive metal layer is a foamed metal mesh with a through-hole structure; or, the conductive metal layer is a porous metal plate or a porous metal foil, and the material of the conductive metal layer is copper. 4. The preparation method according to claim 1, wherein, in step (a), the plurality of stainless steel wires are laid crosswise, so as to form mutually cross-connected channels on the porous electrode current collector. 5. The preparation method according to claim 1, wherein, in step (a), the diameter of the stainless steel wire is 0.5-5mm. 6. The preparation method according to claim 1, wherein, in step (b), the heating temperature is 50-200°C. 7. The preparation method according to claim 1, wherein, in step (b), the applied pressure is 2-20 MPa. 8 . The preparation method according to claim 1 , wherein, in step (c), the planar part of the porous electrode current collector is combined with the separator by bonding or planar thermocompression.

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