CN109888150B - Lithium battery separator, wound product and wound lithium battery - Google Patents
Lithium battery separator, wound product and wound lithium battery Download PDFInfo
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- CN109888150B CN109888150B CN201910092448.3A CN201910092448A CN109888150B CN 109888150 B CN109888150 B CN 109888150B CN 201910092448 A CN201910092448 A CN 201910092448A CN 109888150 B CN109888150 B CN 109888150B
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- lithium
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- negative electrode
- shaped barrier
- strip
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- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 187
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 161
- 238000000576 coating method Methods 0.000 claims abstract description 129
- 239000011248 coating agent Substances 0.000 claims abstract description 126
- 230000004888 barrier function Effects 0.000 claims abstract description 114
- 238000004804 winding Methods 0.000 claims abstract description 13
- 229910001416 lithium ion Inorganic materials 0.000 claims description 14
- 238000013507 mapping Methods 0.000 claims description 14
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 11
- 230000008859 change Effects 0.000 claims description 8
- -1 polytetrafluoroethylene Polymers 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 230000005012 migration Effects 0.000 claims description 4
- 238000013508 migration Methods 0.000 claims description 4
- 239000004593 Epoxy Substances 0.000 claims 1
- 229920005549 butyl rubber Polymers 0.000 claims 1
- 238000006557 surface reaction Methods 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 13
- 238000006243 chemical reaction Methods 0.000 abstract description 12
- 230000008569 process Effects 0.000 abstract description 11
- 239000000853 adhesive Substances 0.000 abstract description 5
- 230000001070 adhesive effect Effects 0.000 abstract description 5
- 238000007599 discharging Methods 0.000 description 13
- 239000002390 adhesive tape Substances 0.000 description 12
- 239000003792 electrolyte Substances 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 9
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical compound O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 description 8
- 239000011247 coating layer Substances 0.000 description 6
- 229910000831 Steel Inorganic materials 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000007649 pad printing Methods 0.000 description 4
- 230000036632 reaction speed Effects 0.000 description 4
- 238000007650 screen-printing Methods 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 239000010959 steel Substances 0.000 description 4
- 230000000903 blocking effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000007773 negative electrode material Substances 0.000 description 3
- 238000007639 printing Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229920000181 Ethylene propylene rubber Polymers 0.000 description 2
- 239000005062 Polybutadiene Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- JPPGWVWBAJLHCE-UHFFFAOYSA-N buta-1,3-diene;ethene Chemical compound C=C.C=CC=C JPPGWVWBAJLHCE-UHFFFAOYSA-N 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 238000003411 electrode reaction Methods 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229920002857 polybutadiene Polymers 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- GPVWCGHDIGTNCE-UHFFFAOYSA-N [Fe](=S)=S.[Li] Chemical compound [Fe](=S)=S.[Li] GPVWCGHDIGTNCE-UHFFFAOYSA-N 0.000 description 1
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 1
- FBDMJGHBCPNRGF-UHFFFAOYSA-M [OH-].[Li+].[O-2].[Mn+2] Chemical compound [OH-].[Li+].[O-2].[Mn+2] FBDMJGHBCPNRGF-UHFFFAOYSA-M 0.000 description 1
- 239000006182 cathode active material Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Primary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention discloses a lithium battery diaphragm, a winding product and a winding type lithium battery, which comprises a diaphragm body, wherein at least one surface of the diaphragm body is coated with at least one strip-shaped barrier coating which continuously extends along the length direction of the diaphragm body, and the strip-shaped barrier coating shields corresponding parts of the surface of the diaphragm body so as to block or slow down the discharge reaction of a lithium negative plate at the corresponding parts, so that a conductive channel of a suppressed lithium metal strip is formed at the corresponding parts of the lithium negative plate corresponding to the strip-shaped barrier coating in the whole battery discharge process; and the influence of the barrier coating on the thickness of the lithium battery diaphragm is less, the adhesive force of the barrier coating and the diaphragm is firm, the separator is not easy to fall off, and the shape and the number can be flexibly set according to the discharge condition of the electrode.
Description
Technical Field
The invention relates to the field of lithium metal batteries, in particular to a lithium battery diaphragm, a winding product and a winding type lithium battery.
Background
Lithium primary batteries such as lithium-manganese dioxide, lithium-argon-sulfuryl chloride and lithium-iron disulfide and part of secondary lithium batteries adopt metal lithium as a negative electrode active material.
The lithium battery winding product is formed by winding a lithium negative plate, a diaphragm and a positive plate which are sequentially laminated.
Because the metal lithium has good conductivity, lithium metal also tends to play a role in negative electrode conductivity when being used as a negative electrode active material, thereby reducing the use of conductive materials and improving the energy density of the lithium battery.
Such a lithium battery may have the following problems: in the discharging process of the battery, lithium metal serving as a conductive material and a cathode active material is continuously consumed along with the discharging process, the consumption cannot be uniformly consumed, a plurality of local parts of the lithium metal are preferentially consumed, when the lithium metal of the local parts is preferentially consumed, an 'island' disconnected from an electrode discharging circuit is formed in the internal area of the consumed part on the electrode, and the 'island' cannot participate in the discharging of the battery, so that the waste of the lithium metal material is caused, and the utilization rate of the cathode material and the capacitance of the battery are reduced.
More serious cases are: in the actual discharging process of the lithium battery, the part of the lithium metal, which is subjected to partial preferential discharging and is broken in advance, is always broken in a linear shape perpendicular to the extending direction of the negative electrode plate, and the part of the lithium metal separated from the negative electrode tab after the linear breaking is directly incapable of participating in the discharging of the battery. Such a linear fracture system greatly reduces the utilization rate of the negative electrode material, and in practice, the electrode is often wound with a high rate of occurrence of linear fracture due to tightness or the like at a portion perpendicular to the winding direction.
In order to overcome the local fracture phenomenon of the lithium negative electrode sheet caused by the nonuniform reaction, a mode of sticking a certain length of adhesive tape on the surface of the lithium negative electrode sheet and sticking the adhesive tape beside a tab is generally adopted, and the surface of the stuck lithium metal is protected in the mode, so that the capacity loss caused by fracture when the lithium metal discharges is improved, but the following problems are caused at the same time: 1. because the adhesive tape has a certain thickness, once the adhesive tape is too long, the diameter of the coil Rao Pin at the adhesive tape attaching area is too large after the electrode is wound, so that the capacity in the limited battery space is reduced, and the energy density of the lithium battery is affected. 2. The adhesive tape is easy to degum, is not tightly attached to the lithium negative electrode sheet, and is difficult to stop the island phenomenon.
Disclosure of Invention
The invention aims to solve the technical problem of providing a lithium battery diaphragm capable of slowing down or blocking lithium ion migration at a local part, and further provides a battery winding product with the lithium battery diaphragm and a lithium metal battery.
The technical scheme for solving the technical problems needs to be provided: the lithium battery diaphragm comprises a diaphragm body, and is characterized in that at least one surface of the diaphragm body is coated with at least one strip-shaped barrier coating which extends continuously along the length direction of the diaphragm body, and the strip-shaped barrier coating shields corresponding parts of the surface of the diaphragm body to form closed holes through which ions cannot pass, so that the discharge reaction of a lithium negative plate at the part where the ions are located is blocked or slowed down, the consumption of the lithium negative plate is slowed down, and a protected conductive belt is formed.
The invention further preferably comprises the following steps: the thickness of the strip-shaped barrier coating is 5-70 mu m; the width of the band-shaped barrier coating can be flexibly adjusted according to the reaction condition of the electrode surface which is required to be blocked until the width is close to the width of the electrode.
The invention further preferably comprises the following steps: the band-shaped barrier coating spans the entire length of the diaphragm body.
The invention further preferably comprises the following steps: the band-shaped barrier coating is in a shape of a single straight line or two or more sections of straight lines or curves.
The invention further preferably comprises the following steps: the band-shaped barrier coating is locally bifurcated.
The invention further preferably comprises the following steps: the strip-shaped barrier coating is distributed at the diagonal position of the diaphragm body in a gradual change mode, and the strip-shaped barrier coating passes through the negative electrode lug of the lithium negative electrode plate and is arranged in the mapping area of the diaphragm body.
The invention further preferably comprises the following steps: the strip-shaped barrier coating is respectively obliquely led to the diagonal positions from the negative electrode lugs of the lithium negative electrode plate at two sides of the mapping area of the diaphragm body.
The invention further preferably comprises the following steps: the barrier coating is formed from a chemically inert coating.
The invention further preferably comprises the following steps: the chemical inert coating is ethylene butadiene rubber, polytetrafluoroethylene or epoxy resin.
The invention further preferably comprises the following steps: the lithium battery separator is formed by jointly winding a positive plate, a lithium negative plate and a lithium battery separator.
The invention further preferably comprises the following steps: a wound lithium battery comprises the battery winding product.
Compared with the prior art, the method has the advantages that the strip-shaped barrier coating is coated on the surface of the lithium battery diaphragm, and the strip-shaped barrier coating shields the corresponding part of the surface of the lithium battery diaphragm body so as to block or slow down the discharge reaction and consumption of the lithium cathode at the corresponding part, so that a suppressed lithium metal strip is formed at the corresponding part on the lithium cathode plate corresponding to the strip-shaped barrier coating; the lithium metal strip is a conductive channel indirectly protected by the strip-shaped barrier coating, and finally, electrode 'islands' are prevented from being formed on the lithium negative plate. Compared with the traditional adhesive tape attached to the lithium negative electrode sheet, the influence of the barrier coating on the diameter of the wound lithium battery electrode sheet is less, the barrier coating does not need to be attached to the surface of the negative electrode, the shape is more diversified, the production efficiency is higher, different numbers and shapes can be flexibly set according to the consumption condition of the lithium negative electrode during discharging of a product, and even profiling printing can be performed. The adhesive force between the barrier coating and the diaphragm is firm, and the separator is not easy to fall off; is also convenient for industrial automatic production.
Drawings
FIG. 1 is a schematic diagram of a battery roll;
FIG. 2 is a schematic diagram of a second embodiment of a battery roll;
FIG. 3 is a schematic illustration of a first barrier coating applied to a negative electrode sheet of a lithium battery;
fig. 4 is a second schematic illustration of a lithium battery negative electrode sheet coated with a barrier coating;
FIG. 5 is a schematic illustration of a first coating of a barrier coating on a lithium battery separator;
FIG. 6 is a schematic illustration of a second coating of a barrier coating on a lithium battery separator;
FIG. 7 is a schematic illustration of a first coating of a barrier coating on a positive plate of a lithium battery;
fig. 8 is a schematic diagram of a second barrier coating applied to a positive plate of a lithium battery.
Detailed Description
The invention is described in further detail below with reference to the embodiments of the drawings.
As shown in fig. 1 and 2, the wound lithium battery includes a steel case, a battery wound product, an electrolyte, and the like. The battery wound product 100 is formed by winding a positive electrode sheet 30, a diaphragm 20 and a lithium negative electrode sheet 10 together, wherein the battery wound product 100 is installed in a steel shell in a cylindrical structure, and electrolyte is filled in the steel shell. The lithium negative plate 10 is connected with a negative electrode lug 11 which is used for being welded at the negative electrode end of the steel shell; manganese dioxide is the main material component of the positive electrode sheet 30.
The working principle of the lithium battery is as follows: the lithium negative plate and the electrolyte react to lose electrons, so that lithium ions are formed and are fused into the electrolyte; the reaction formula:
Li→Li++e
Lithium ions dissolved by the lithium cathode migrate into the positive plate through the electrolyte; taking lithium manganese as an example reaction formula:
MnO2+Li++e→MnO2(Li+)；
the negative electrode is in a gradual process of consumption throughout the chemical reaction.
The diaphragm separates the lithium negative plate from the positive plate, and avoids short circuit caused by direct contact between the lithium negative plate and the positive plate. The separator is usually made of polyethylene porous membrane material, and lithium ions in the lithium negative plate can migrate into the positive plate through the separator.
The method for improving the utilization rate of the metal lithium electrode by coating the insulating material comprises the following specific steps: the surface of the lithium negative electrode sheet 10 or the surface of the corresponding diaphragm 20 or the surface of the positive electrode sheet 30 is coated with a strip-shaped barrier coating 40 to shield or shade the corresponding parts on the surface of the lithium negative electrode sheet 10, and the lithium metal at the corresponding parts is inhibited from discharging reaction due to shielding or shading in the discharging process, and the parts are finally consumed, so that a protected conductive channel is formed on the lithium negative electrode sheet 10 in the later stage of discharging the battery, various islands are prevented from being formed on the lithium negative electrode sheet 10 in the later stage of discharging, and the effect of improving the utilization rate of the lithium negative electrode sheet 10 is achieved.
The surface of the lithium negative electrode sheet 10 or the surface of the corresponding diaphragm 20 or the surface of the positive electrode sheet 30 is coated with a strip-shaped barrier coating 40 to shield or shade the corresponding part of the surface of the lithium negative electrode sheet 10, a protected conductive channel is formed on the lithium negative electrode sheet 10 when the battery discharges, and the lithium metal strip is the conductive channel directly or indirectly protected by the strip-shaped barrier coating 40, so that the formation of electrode 'islands' on the lithium negative electrode sheet 10 is finally avoided. Compared with the traditional adhesive tape attached to the lithium negative electrode sheet, the barrier coating 40 can be coated longer and can penetrate through the whole lithium negative electrode sheet, so that the effect of preventing island generation is better, the influence on the diameter or shape of the wound product 100 after the lithium negative electrode sheet 10, the diaphragm paper 20 and the positive electrode sheet 30 are wound together is less, the adhesive force between the barrier coating 40 and the attachments is firm, and the lithium negative electrode sheet is not easy to fall off; the strip-shaped barrier coating 40 adopts a printing process, has high production efficiency, is convenient for industrial automatic production, and particularly has the production efficiency for the multi-section and multi-strip-shaped barrier coating 40 which is far higher than that of the traditional adhesive tape attaching process.
The thickness of the band-shaped barrier coating 40 is 5-70 μm; the thickness is preferably 10-45 mu m; the thickness of the strip-shaped barrier coating 40 is used for meeting the requirement of shielding the corresponding part of the surface of the positive plate, and blocking or slowing down the consumption of lithium ions of the negative plate due to the dissolution from the surface; while not substantially affecting the diameter of the formed coil. The width of the band-shaped barrier coating is 1-6mm, preferably 2-4mm. The lithium ion-blocking positive electrode plate can meet the requirement of blocking lithium ions from entering the positive electrode plate, and the capacity of the manganese dioxide positive electrode plate required by participation in discharge can not be influenced.
The band-shaped barrier coating 40 spans the entire length of the lithium negative electrode sheet 10 or separator 20 or positive electrode sheet 30, and the shapes of the lithium negative electrode sheet 10, positive electrode sheet 30, and separator 20 are substantially equivalent; the strip-shaped barrier coating 40 can shield or block or inhibit the lithium metal on the surface of the corresponding part on the lithium negative electrode plate 10 from participating in the reaction, so that the vertical linear fracture on the whole lithium negative electrode plate is finally avoided, and the whole lithium negative electrode plate can participate in the discharge cycle of the battery.
The band-shaped barrier coating 40 has a shape of a single straight line or two sections of straight line or wavy line, and if necessary, there may be two or more band-shaped barrier coatings 40 and bifurcations in the same section. The coating of the barrier coating 40 on the surface of the positive plate 30 can adopt pad printing, screen printing, spraying and other processes, so that the production efficiency is high.
The strip-shaped barrier coating 40 on the lithium negative electrode sheet 10 passes through the negative electrode tab 11, or the strip-shaped barrier coating 40 on the diaphragm 20 passes through the mapping area of the negative electrode tab 11 on the diaphragm 20; or the band-shaped barrier coating 40 on the positive electrode tab 30 passes through the mapped region of the negative electrode tab 11 on the positive electrode tab 30.
The coating surface of the lithium negative electrode sheet 10 is the surface which reacts with the positive electrode sheet; or the coated side of the positive electrode sheet 30 is the side that reacts with the lithium negative electrode sheet 10.
The specific distribution of the tape-like barrier coating 40 is as follows:
the band-shaped barrier coating 40 is distributed at diagonal positions of the lithium anode sheet 10 in a gradual change; or band-shaped barrier coating 40 is distributed in a gradual change at diagonal positions of septum 20; or the band-shaped barrier coating 40 is distributed at diagonal positions of the positive electrode sheet 30 in a gradual change;
The band-shaped barrier coating 40 is obliquely directed to diagonal positions from both sides of the negative electrode tab 11 of the lithium negative electrode tab 10, respectively; or the band-shaped barrier coating 40 is obliquely directed to diagonal positions from both sides of the mapping region of the negative electrode tab 11 of the lithium negative electrode tab 10 on the separator 20, respectively; or the band-shaped barrier coating 40 is obliquely directed to a diagonal position from both sides of the mapping region of the negative electrode tab 11 of the lithium negative electrode tab 10 on the positive electrode tab 30, respectively.
When the lithium negative electrode sheet 10, the separator 20 and the positive electrode sheet 30 are wound to form a wound product, the thickness of the band-shaped barrier coating 40 is dispersed in the vertical direction of the whole cylindrical wound product, and compared with the thickness, the diameter of the wound product is not obviously increased, the capacity of the electrolyte is not obviously affected, and the discharge performance of the battery is not affected.
The barrier coating is made of a chemically inert coating. The chemical inert coating is ethylene butadiene rubber, polytetrafluoroethylene or epoxy resin, has stable electrochemical performance, can not be dissolved in electrolyte of the battery, and can not participate in the discharging process of the battery.
In particular for the negative electrode sheet of a lithium battery,
For the negative electrode sheet of a lithium battery, such a coating layer provided on the surface of the negative electrode of the lithium battery is called a "barrier coating layer", and may have conductivity, such as a conductive paste which is stable in an electrolyte and does not exert a chemical or electrochemical influence on the negative electrode of the lithium battery, to which conductive graphite and carbon black are added, in addition to a coating material such as ethylene propylene rubber, PTFE or the like having an insulating effect, unlike a coating layer provided on a separator,
As shown in fig. 3 and 4, the lithium battery negative electrode sheet comprises a lithium negative electrode sheet body and a negative electrode tab 11, wherein one surface of the lithium negative electrode sheet body is coated with a strip-shaped barrier coating 40 which continuously extends along the length direction of the lithium negative electrode sheet body, namely the lithium negative electrode sheet 10 described in the embodiment; the strip-shaped barrier coating 40 passes through the negative electrode tab 11, and the strip-shaped barrier coating 40 shields the corresponding part of the surface of the lithium negative electrode sheet body so as to form a protected conductive channel S on the lithium negative electrode sheet 10 and delay the discharge reaction speed of the corresponding part.
The surface of the lithium negative electrode sheet 10 is coated with the strip-shaped barrier coating 40, and the strip-shaped barrier coating 40 shields the corresponding part of the surface of the lithium negative electrode sheet body so as to delay the discharge reaction speed of the corresponding part, and a protected conductive channel S which is always connected with the negative electrode tab 11 is formed on the lithium negative electrode sheet 10, so that electrode 'island' is avoided. Compared with the traditional adhesive tape attached to the lithium negative plate, the barrier coating 40 has less influence on the thickness of the lithium battery negative plate, is more reliably connected with the lithium negative plate 10, and is also convenient for industrial automatic production.
The strip-shaped barrier coating 40 spans the entire length of the lithium negative electrode sheet 10, so that vertical linear breakage of the entire lithium metal can be avoided, and the entire lithium negative electrode sheet can participate in the discharge cycle of the battery.
The band-shaped insulating coating 40 has a shape of a single straight line or two straight lines or a wavy line, and a plurality of insulating coatings may be provided according to the condition of electrode reaction if necessary, and may have a bifurcation. The coating of the barrier coating 40 on the surface of the lithium negative electrode sheet 10 may be performed by pad printing, screen printing, spraying, or the like.
The specific distribution of the band-shaped barrier coating is as follows: 1. the band-shaped barrier coating 40 passing through the negative electrode tab 11 is distributed at diagonal positions of the lithium negative electrode sheet 10 in a gradual change. 2. The band-shaped barrier coating 40 is directed obliquely to the diagonal position from each of both sides of the negative electrode tab 11. When the lithium negative electrode sheet 10, the diaphragm 20 and the positive electrode sheet 30 are wound to form a wound product, the thickness of the strip-shaped barrier coating is dispersed in the vertical direction of the whole columnar wound product, and compared with the barrier coating which is parallel to the transverse distribution of the lithium negative electrode sheet, the diameter of the wound product is not obviously increased, the capacity of electrolyte is not obviously influenced, and the discharge performance of a battery is not influenced.
In the case of a separator for a lithium battery,
As shown in fig. 5 and 6, the lithium battery separator comprises a separator body, wherein one surface of the separator body is coated with a strip-shaped barrier coating 40 which extends continuously along the length direction of the separator body, and the strip-shaped barrier coating 40 shields the corresponding part of the surface of the separator body so as to block or slow down the migration of lithium ions generated by the lithium negative electrode sheet 10 and delay the discharge reaction speed of the corresponding part of the lithium negative electrode sheet 10 corresponding to the strip-shaped barrier coating. The above-described diaphragm body, that is, the diaphragm 20 in the present embodiment.
The surface of the lithium battery diaphragm 20 is coated with a strip-shaped barrier coating 40, and the strip-shaped barrier coating 40 shields the corresponding part of the surface of the lithium battery diaphragm 20 so as to block or slow down the migration of lithium ions generated by the lithium negative electrode sheet 10, thereby forming a suppressed lithium metal strip at the corresponding part of the lithium negative electrode sheet 10 corresponding to the strip-shaped barrier coating 40; the lithium metal strip is a conductive channel S protected by a strip-shaped barrier coating, and finally, electrode "islands" are avoided from forming on the lithium negative electrode sheet 10. Compared with the traditional adhesive tape attached to the lithium negative plate, the influence of the barrier coating 40 on the thickness of the lithium battery diaphragm 20 is less, the adhesive force between the barrier coating 40 and the diaphragm 20 is firm, and the lithium battery diaphragm is not easy to fall off; is also convenient for industrial automatic production.
The band-shaped barrier coating 40 spans the entire length of the separator 20, the length of the separator 20 being substantially equivalent to the length of the lithium negative electrode sheet 10; the strip-shaped barrier coating 40 on the diaphragm 20 can inhibit the lithium metal on the corresponding lithium negative electrode sheet 10 from participating in the reaction, so that the vertical linear fracture of the whole lithium metal is finally avoided, and the whole lithium negative electrode sheet 10 can participate in the discharge cycle of the battery.
The band-shaped barrier coating 40 is in the shape of a single straight line or two sections of straight lines or wavy lines, and the barrier coating 40 can be coated on the surface of the diaphragm by adopting pad printing, screen printing, spraying and other processes.
The specific distribution of the band-shaped barrier coating is as follows: 1. the band-shaped barrier coating 40 is distributed at the diagonal position of the separator body in a gradual change, and the band-shaped barrier coating 40 passes through the negative electrode tab 11 of the lithium negative electrode tab 10 and is in the mapping region of the separator body. 2. The band-shaped barrier coating 40 is obliquely directed to diagonal positions from the negative electrode tab 11 of the lithium negative electrode tab 10 on both sides of the mapping region of the separator body, respectively. The lithium negative electrode sheet 10, the separator 20 and the positive electrode sheet 30 have the same shape and size, and after the three are laminated and wound into a wound product, the mapping area is the position area of the separator 20 and the positive electrode sheet 30 corresponding to the lithium negative electrode sheet 10.
For the positive electrode sheet of a lithium battery, such a coating layer provided on the positive electrode surface of the lithium battery is also called a "barrier coating layer", and may have conductivity, such as a conductive paste which is stable in an electrolyte and does not chemically or electrochemically affect the negative electrode of lithium, to which conductive graphite and carbon black are added, in addition to a coating material such as ethylene propylene rubber, PTFE, etc., having an insulating effect, unlike a coating layer provided on a separator.
As shown in fig. 7 and 8, the positive electrode sheet for a lithium battery includes a positive electrode sheet body, that is, a positive electrode sheet 30 in the present embodiment; one surface of the positive plate 30 is coated with a strip-shaped barrier coating 40 which continuously extends along the length direction of the positive plate 30, and the strip-shaped barrier coating 40 shields corresponding parts of the surface of the positive plate 30 so as to block or slow down lithium ions generated by the lithium negative plate 10 at corresponding parts from entering the positive plate 30, and delay the discharge reaction speed of the corresponding parts corresponding to the strip-shaped barrier coating 40 on the lithium negative plate 10 at the corresponding parts, so that the lithium negative electrode at the corresponding parts becomes a current channel.
The surface of the positive plate 30 of the lithium battery is coated with a strip-shaped barrier coating 40, and the strip-shaped barrier coating 40 shields the corresponding part of the surface of the positive plate 30 of the lithium battery so as to block or slow down lithium ions generated by the negative plate 10 from entering the positive plate 30, thereby forming a suppressed lithium metal strip at the corresponding part of the negative plate 10 corresponding to the strip-shaped barrier coating 40; the lithium metal strip is a conductive path S indirectly protected by the strip-shaped barrier coating, and finally, the formation of current "islands" on the lithium negative electrode sheet 10 is avoided. Compared with the traditional adhesive tape attached to the lithium negative electrode plate, the barrier coating 40 has less influence on the thickness of the lithium battery positive electrode plate, has firm adhesive force with the diaphragm, is not easy to fall off, can be used for printing complex shapes and stripes, and has more various and complex functions of protecting the surface of the lithium negative electrode; is also convenient for industrial automatic production.
The band-shaped barrier coating 40 spans the entire length of the positive electrode sheet 30, the length of the positive electrode sheet 30 being substantially equivalent to the length of the lithium negative electrode sheet 10; the strip-shaped barrier coating 40 on the positive plate 30 can inhibit the lithium metal on the corresponding lithium negative plate 10 from participating in the reaction, so that the vertical linear fracture of the whole lithium metal is finally avoided, and the whole lithium negative plate can participate in the discharge cycle of the battery.
The band-shaped barrier coating 40 has a shape of a single straight line or two straight lines or a wavy line, and a plurality of barrier coatings may be provided according to the condition of the electrode reaction if necessary, and may have a bifurcation. The application of the barrier coating 40 to the surface of the positive electrode sheet 30 may be by pad printing, screen printing, spraying, or the like.
The specific distribution of the tape-like barrier coating 40 is as follows: 1. the band-shaped barrier coating 40 is distributed at the diagonal position of the positive electrode tab 30 in a gradual change, and the band-shaped barrier coating 40 passes through the negative electrode tab 11 of the lithium negative electrode tab 10 at the mapping region of the positive electrode tab 30. 2. The band-shaped barrier coating 40 is obliquely directed to diagonal positions from the negative electrode tab 11 of the lithium negative electrode tab 10 on both sides of the mapping region of the positive electrode tab 30, respectively. The lithium negative electrode sheet 10, the separator 20 and the positive electrode sheet 30 have the same shape and size, and after the three are laminated and wound into a wound product, the mapping area is the position area of the separator 20 and the positive electrode sheet 30 corresponding to the lithium negative electrode sheet 10.
When the above-mentioned lithium negative electrode sheet 10, separator 20 and positive electrode sheet 30 are wound to form a wound product, the thickness of the band-shaped barrier coating 40 is dispersed in the vertical direction of the entire cylindrical wound product, and in comparison, the diameter of the wound product is not significantly increased, the capacity of the electrolyte is not significantly affected, and the discharge performance of the battery is not affected.
The lithium battery negative electrode sheet, the wound product and the wound lithium battery provided by the invention are described in detail, and specific examples are applied to illustrate the principles and the embodiments of the invention, and the description of the examples is only used for helping to understand the invention and the core idea. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (6)
1. The lithium battery diaphragm comprises a diaphragm body, and is characterized in that at least one surface of the diaphragm body is coated with at least one strip-shaped barrier coating which extends continuously along the length direction of the diaphragm body, and the strip-shaped barrier coating shields the corresponding part of the surface of the diaphragm body so as to block or slow down the migration of lithium ions of a lithium negative plate at the mapping part;
The band-shaped barrier coating spans the entire length of the diaphragm body;
The strip-shaped barrier coating is distributed at the diagonal position of the diaphragm body in a gradual change manner, and passes through the negative electrode lug of the lithium negative electrode plate to be in the mapping area of the diaphragm body; or the strip-shaped barrier coating is respectively obliquely led to the diagonal positions from the two sides of the mapping area of the diaphragm body on the negative electrode lug of the lithium negative electrode plate.
2. The lithium battery separator according to claim 1, characterized in that the thickness of the band-shaped barrier coating is 5-70 μm; the width of the band-shaped barrier coating can be adjusted according to the electrode surface reaction condition which is blocked by the requirement.
3. The lithium battery separator of claim 1, wherein said band-shaped barrier coating is comprised of an insulating and chemically inert coating.
4. A lithium battery separator according to claim 3, wherein the chemically inert coating is butyl rubber, polytetrafluoroethylene or epoxy.
5. A battery wound product, characterized in that the battery wound product is formed by winding a positive plate, a lithium negative plate and the lithium battery diaphragm according to any one of claims 1-4 together.
6. A wound lithium battery comprising the battery winding of claim 5.
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| CN201910092448.3A CN109888150B (en) | 2019-01-30 | 2019-01-30 | Lithium battery separator, wound product and wound lithium battery |
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| CN109888150A CN109888150A (en) | 2019-06-14 |
| CN109888150B true CN109888150B (en) | 2024-04-30 |
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| EP4099494A4 (en) * | 2020-01-31 | 2024-01-10 | Panasonic Ip Man Co Ltd | Non-aqueous electrolyte secondary battery |
| WO2023000289A1 (en) * | 2021-07-23 | 2023-01-26 | 宁德时代新能源科技股份有限公司 | Battery assembly and processing method and apparatus, battery cell, battery and electric device |
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| CN209401717U (en) * | 2019-01-30 | 2019-09-17 | 中银（宁波）电池有限公司 | Lithium battery diaphragm, winding product and coiling type lithium battery |
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| JPH09180761A (en) * | 1995-12-27 | 1997-07-11 | Fuji Elelctrochem Co Ltd | Spiral lithium ion secondary battery |
| CN205542997U (en) * | 2015-12-21 | 2016-08-31 | 江西迪比科股份有限公司 | Polyvinylidene fluoride coating non -woven fabrics diaphragm paper polymer lithium ion secondary cell |
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