CN115714164A - Preparation method of pole piece, positive pole piece and lithium ion battery - Google Patents
Preparation method of pole piece, positive pole piece and lithium ion battery Download PDFInfo
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- CN115714164A CN115714164A CN202211442640.9A CN202211442640A CN115714164A CN 115714164 A CN115714164 A CN 115714164A CN 202211442640 A CN202211442640 A CN 202211442640A CN 115714164 A CN115714164 A CN 115714164A
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Abstract
The application discloses a preparation method of a pole piece, a positive pole piece and a lithium ion battery, wherein the preparation method of the pole piece comprises the following steps: coating the solid electrolyte slurry on a diaphragm to prepare and form a composite diaphragm; and the side of the composite diaphragm coated with the solid electrolyte slurry is opposite to a pole piece to be processed, and the solid electrolyte on the composite diaphragm is transferred to the surface of the pole piece to be processed by hot pressing to form a solid electrolyte layer so as to prepare and form the target pole piece. The preparation method of the pole piece, the positive pole piece and the lithium ion battery can solve the problem that the pole piece is curled and bent in the process of coating the solid electrolyte.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a preparation method of a pole piece, a positive pole piece and a lithium ion battery.
Background
Lithium ion batteries are widely used in the fields of portable electronic devices, smart grids, new energy vehicles, and the like because of their advantages of light weight, high energy density, long life, and the like. The traditional lithium ion battery uses liquid electrolyte, but the flash point of the liquid electrolyte is lower, and the electrolyte is possibly heated and spontaneously combusted under abnormal conditions such as large-current discharge, overcharge and internal short circuit, and even the safety problems such as explosion are caused. The solid-state lithium ion battery uses non-combustible or non-combustible solid electrolyte to replace combustible organic electrolyte in the traditional lithium ion battery, so that the safety problem of the lithium ion battery can be fundamentally solved, and the service temperature range, the cycle life and the energy density of the lithium ion battery can be further improved.
For a solid lithium ion battery, coating a solid electrolyte layer on the surface of a positive electrode active material layer is beneficial to improving the safety of the solid lithium ion battery, and the current method for coating a solid electrolyte film on the surface of a positive electrode is as follows: 1. directly coating the solid electrolyte on the surface of the positive active material layer, firstly preparing a solid electrolyte film on a release film, and then separating at the later stage; however, the above methods all have various disadvantages, for example, when the surface of the positive active material layer is coated with the solid electrolyte slurry, the pole piece is easily curled and bent due to solvent volatilization in the drying process; the release film and the solid electrolyte film have low bonding strength and poor support property, and an ultrathin, stable and difficult-to-break solid electrolyte layer (< 5 microns) cannot be coated on the surface of the positive electrode and also faces the difficult problem of curling.
Therefore, how to avoid the curling and bending of the pole piece in the process of coating the solid electrolyte becomes a technical problem to be solved by the technical personnel in the field.
Disclosure of Invention
The application provides a preparation method of a pole piece, a positive pole piece and a lithium ion battery, which can solve the problem that the pole piece is curled and bent in the process of coating a solid electrolyte.
In order to solve one or more of the above technical problems, the present application adopts the following technical solutions:
in a first aspect, the present application provides a method for preparing a pole piece, where the method for preparing a pole piece includes:
coating the solid electrolyte slurry on a diaphragm to prepare and form a composite diaphragm;
and the side of the composite diaphragm coated with the solid electrolyte slurry is opposite to the pole piece to be processed, and the solid electrolyte on the composite diaphragm is transferred to the surface of the pole piece to be processed by hot pressing to form a solid electrolyte layer so as to prepare and form the target pole piece.
Furthermore, both sides of the pole piece to be processed are covered with solid electrolyte layers.
Further, the pole piece to be processed comprises a current collector and an active substance layer coated on the surface of the current collector.
Further, the solid electrolyte on the composite diaphragm is transferred to two sides of the pole piece to be processed in a rolling mode.
Further, the solid electrolyte slurry includes a solid electrolyte including an inorganic solid electrolyte.
The inorganic solid electrolyte may comprise one or more solid electrolyte particles, preferably the solid electrolyte particles may comprise particles of one or more oxides, sulfides, halides, borates, nitrides or hydrides.
As an embodiment, the oxide particles may comprise one or more of garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, the one or more garnet ceramics may be selected from the group comprising: li 6.5 La 3 Zr 1.75 Te 0.25 O 12 、Li 7 La 3 Zr 2 O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr 2 O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La 3 Zr 2 O 12 、Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 、Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 And combinations thereof. The one or more LISICON-type oxides may be selected from the group comprising: li 14 Zn(GeO 4 ) 4 、Li 3+x (P 1-x Si x )O 4 (where 0 < x < 1), li 3+x Ge x V 1-x O 4 (where 0 < x < 1), and combinations thereof. The one or more NASICON type oxides may be formed from LiMM' (PO) 4 ) 3 Definitions, wherein M and M' are independently selected from Al, ge, ti, sn, hf, zr, and La. For example, in certain variations, the one or more NASICON-type oxides may be selected from the group consisting of: li 1+x Al x Ge 2-x (PO 4 ) 3 (LAGP) (wherein x is 0. Ltoreq. X.ltoreq.2), li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP) (where 0. Ltoreq. X. Ltoreq.2), li 1+x Y x Zr 2-x (PO 4 ) 3 (LYZP) (wherein x is 0. Ltoreq. X.ltoreq.2), li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 、LiTi 2 (PO 4 ) 3 、LiGeTi(PO 4 ) 3 、LiGe 2 (PO 4 ) 3 、LiHf 2 (PO 4 ) 3 And combinations thereof. The one or more perovskite-type ceramics may be selected from the group comprising: li 3.3 La 0.53 TiO 3 、LiSr 1.65 Zr 1.3 Ta 1.7 O 9 、Li 2x-y Sr 1-x Ta y Zr 1-y O 3 (where x =0.75y and 0.60 < y < 0.75), li 3/8 Sr 7/16 Nb 3/4 Zr 1/4 O 3 、Li 3x La (2/3-x) TiO 3 (where 0 < x < 0.25), and combinations thereof. In one variation, the one or more oxide-based materials may have a thickness of greater than or equal to about 10 -5 S/cm to less than or equal to about 10 - 1 Ion electricity of S/cmAnd (4) conductivity.
In various aspects, the sulfide-based particles may include one or more sulfide-based materials selected from the group consisting of: li 2 S-P 2 S 5 、Li 2 S-P 2 S 5 -MS x (wherein M is Si, ge or Sn and 0. Ltoreq. X. Ltoreq.2), li 3.4 Si 0.4 P 0.6 S 4 、Li 10 GeP 2 S 11.7 O 0.3 、Li 9.6 P 3 S 12 、Li 7 P 3 S 11 、Li 9 P 3 S 9 O 3 、Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 10 (Si 0.5 Ge 0.5 )P 2 S 12 、Li(Ge 0.5 Sn 0.5 )P 2 S 12 、Li(Si 0.5 Sn 0.5 )PsS 12 、Li 10 GeP 2 S 12 (LGPS)、Li 6 PS 5 X (wherein X is Cl, br or I), li 7 P 2 S 8 I、Li 10.35 Ge 1.35 P 1.65 S 12 、Li 3.25 Ge 0.25 P 0.75 S 4 、Li 10 SnP 2 S 12 、Li 10 SiP 2 S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 C 10.3 、 (1-x) P 2 S 5-x Li 2 S (wherein 0.5. Ltoreq. X. Ltoreq.0.7) and combinations thereof. In one variation, the one or more sulfide-based materials may have a composition of greater than or equal to about 10 -7 An ionic conductivity of S/cm to less than or equal to about 1S/cm.
In various aspects, the halide-based particles can include one or more halide-based materials selected from the group consisting of: li 2 CdC 14 、Li 2 MgC 14 、Li 2 Cd I4 、Li 2 ZnI 4 、Li 3 OCl、LiI、Li 5 ZnI 4 、Li 3 OCl 1-x Br x (wherein 0 <)x < 1) and combinations thereof. In one variation, the one or more halide-based materials can have a composition of greater than or equal to about 10 -8 S/cm to less than or equal to about 10 -1 Ion conductivity of S/cm.
In various aspects, the borate-based particles may include one or more borate-based materials selected from the group consisting of: li 2 B 4 O 7 、Li 2 O-(B 2 O 3 )-(P 2 O 5 ) And combinations thereof. In one variation, the one or more borate-based materials may have a thickness of greater than or equal to about 10 -7 S/cm to less than or equal to about 10 -2 Ion conductivity of S/cm.
In various aspects, the nitride-based particles may include one or more nitride-based materials selected from the group consisting of: li 3 N、Li 7 PN 4 、LiSi 2 N 3 LiPON, and combinations thereof. In one variation, the one or more nitride-based materials may have a thickness of greater than or equal to about 10 -9 An ionic conductivity of S/cm to less than or equal to about 1S/cm.
In various aspects, the hydride-based particles can include one or more hydride-based materials from the group of: li 3 AlH 6 、LiBH 4 、LiBH 4 LiX (where X is one of Cl, br and I), liNH 2 、Li 2 NH、LiBH 4 -LiNH 2 And combinations thereof. In one variation, the one or more hydride-based materials can have a thickness of greater than or equal to about 10 -7 S/cm to less than or equal to about 10 -2 Ion conductivity of S/cm.
In further variations, the solid electrolyte particles may be one or more metal oxide particles or lithium-containing compounds, including but not limited to Al 2 O 3 、SiO 2 、TiO 2 、LiNbO 3 、Li 4 Ti 5 O 4 、Li 3 PO 4 。
Further, the solid electrolyte also comprises a polymer solid electrolyte, and preferably, the solid electrolyte is a composite solid electrolyte composed of a polymer solid electrolyte and an inorganic solid electrolyte.
Further, the polymer solid electrolyte includes at least one of polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyethylene oxide (PEO).
Further, the solid electrolyte slurry further comprises at least one of a binder and a lithium salt.
Further, the binder includes polyethylene glycol, polyethylene oxide (PEO), poly (p-phenylene oxide) (PPO), poly (methyl methacrylate) (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyvinyl chloride (PVC), and combinations thereof, and the like, and may be selected according to actual needs without departing from the inventive concept of the present application, and is not specifically limited herein.
Further, the lithium salt includes lithium hexafluorophosphate (LiPF) 6 ) Lithium perchlorate (LiClO) 4 ) Lithium aluminum tetrachloride (LiAlCl) 4 ) Lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF) 4 ) Lithium difluorooxalato borate (LiBF) 2 (C 2 O 4 ) (LiODFB), lithium tetraphenylborate (LiB (C)) 6 H 5 ) 4 ) Lithium bis (oxalato) borate (LiB (C) 2 O 4 ) 2 ) (LiBOB) and lithium tetrafluoro oxalate phosphate (LiPF) 4 (C 2 O 4 ) (LiFOP), lithium nitrate (LiNO) 3 ) Lithium hexafluoroarsenate (LiA) s F 6 ) Lithium trifluoromethanesulfonate (LiCF) 3 SO 3 ) Lithium bis (trifluoromethanesulfonylimide) (LITFSI) (LiN (CF) 3 SO 2 ) 2 ) Lithium bis (fluorosulfonylimide) (LiN (FSO) 2 ) 2 ) (LIFSI) and combinations thereof. In certain variations, the lithium salt is selected from lithium hexafluorophosphate (LiPF) 6 ) Bis (trifluoromethanesulfonylimide) Lithium (LiTFSI) (LiN (CF) 3 SO 2 ) 2 ) Lithium bis (fluorosulfonyl) imide (LiN (FSO) 2 ) 2 ) (LiFSI), fluoroalkyl lithium phosphonate (LiFAP), lithium phosphate (Li) 3 PO 4 ) And combinations thereof.
Further, the thickness of the solid electrolyte layer is 1-20 microns.
Preferably, the thickness of the solid electrolyte layer is 2 to 6 micrometers.
Further, the hot pressing temperature is 80-110 ℃.
Further, the coating speed is 5-30m/min.
In a second aspect, the application also provides a positive pole piece, and the positive pole piece is prepared by the preparation method of the pole piece.
Further, the positive pole piece comprises a positive pole current collector, a positive pole active material layer covering the surface of the positive pole current collector, and a solid electrolyte layer covering the surface of the positive pole active material layer.
Further, the positive electrode active material layer includes a positive electrode active material including a plurality of positive electrode active particles of one or more transition metal cations, the transition metal including manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof.
Further, the positive electrode active material may be one of a layered oxide, spinel, and polyanion.
In a third aspect, the present application further provides a lithium ion battery, where the lithium ion battery includes the above-mentioned positive electrode plate, negative electrode plate, and diaphragm, and the diaphragm is disposed between the positive electrode plate and the negative electrode plate.
Further, the negative electrode plate comprises a negative electrode current collector and a negative electrode active material layer formed on the negative electrode current collector. The negative electrode current collector includes, but is not limited to, aluminum, copper, nickel, or zinc, etc. The negative electrode active material layer includes a negative electrode binder, a negative electrode active material, and a negative electrode conductive agent.
According to the specific embodiments provided herein, the present application discloses the following technical effects:
the solid electrolyte slurry is coated on the diaphragm, and the stripping force between the solid electrolyte slurry and the diaphragm is moderate, so that the difficulty in stripping the solid electrolyte layer and the diaphragm caused by overlarge stripping force between the solid electrolyte layer and the diaphragm is avoided, and the composite effect between the solid electrolyte layer and a pole piece is not influenced; and the hot pressing effect in the hot pressing process can not be influenced because the peeling force of the solid electrolyte layer and the diaphragm is too small, so that the solid electrolyte layer cannot be compounded with the diaphragm in the previous period. In addition, in the hot-pressing process, the pole piece is in a tight state and is heated to enable the solvent to be fully volatilized, so that the pole piece is prevented from being curled and bent when being coated with the solid electrolyte.
Meanwhile, in the application, the coating process of the solid electrolyte and the diaphragm and the rolling process of the composite diaphragm and the pole piece are well integrated, and the composite diaphragm and the pole piece are compounded under the condition that the solid electrolyte is not dried, so that the interface bonding capability and the interface performance of the pole piece and the solid electrolyte film on the diaphragm are improved.
The application makes up the problem that the adhesive force of the existing release film is not strong through the specific binding force between the wet rolling and the diaphragm.
Of course, it is not necessary for any product to achieve all of the above-described advantages at the same time for the practice of the present application.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for manufacturing a pole piece according to an embodiment of the present disclosure.
Fig. 2 is a schematic structural diagram of a device for manufacturing a pole piece according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of an intermediate product in a hot pressing process.
Fig. 4 is a schematic structural view of a pole piece coated with a solid electrolyte layer.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely below, and it should be understood that the described embodiments are only a part of the embodiments of the present application, and not all embodiments. All other embodiments that can be derived from the embodiments given herein by a person of ordinary skill in the art are intended to be within the scope of the present disclosure.
As described in the background art, for the solid-state lithium ion battery, coating the solid electrolyte layer on the surface of the positive electrode active material layer helps to improve the safety of the solid-state lithium ion battery, but in the conventional coating process, the solvent volatilization of the coated solid electrolyte layer can cause the pole piece to curl and bend. Therefore, the application provides a preparation method of a pole piece, a positive pole piece and a lithium ion battery, which can solve the problem that the pole piece is curled and bent when being coated with a solid electrolyte.
Fig. 1 is a flowchart of a method for manufacturing a pole piece according to an embodiment of the present application, and as shown in fig. 1, the method for manufacturing a pole piece includes:
s1: and coating the solid electrolyte slurry on the diaphragm to prepare and form the composite diaphragm.
The solid electrolyte slurry comprises a solid electrolyte, and the solid electrolyte has better chemical inertness to electrolyte or liquid additives in the battery, so that the safety performance of the battery is greatly improved. The solid electrolyte herein may be a fast ion conductor or a metal oxide, wherein the fast ion conductor is also called a lithium ion conductive material, which generally refers to a material having a better ion conductive property. The fast ion conductor in the present application comprises an inorganic solid state electrolyte, which may comprise one or more solid state electrolyte particles, preferably the solid state electrolyte particles may comprise particles of one or more oxides, sulfides, halides, borates, nitrides or hydrides.
As an embodiment, the oxide particles may comprise one or more of garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, the one or more garnet ceramics may be selected from the group comprising: li 6.5 La 3 Zr 1.75 Te 0.25 O 12 、Li 7 La 3 Zr 2 O 12 、Li 6.2 Ga 0.3 La 2.95 Rb 0.05 Zr 2 O 12 、Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 、Li 6.25 Al 0.25 La 3 Zr 2 O 12 、Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 、Li 6.75 La 3 Zr 1.75 Nb 0.25 O 12 And combinations thereof. The one or more LISICON-type oxides may be selected from the group comprising: li 14 Zn(GeO 4 ) 4 、Li 3+x (P 1-x Si x )O 4 (where 0 < x < 1), li 3+x Ge x V 1-x O 4 (where 0 < x < 1), and combinations thereof. The one or more NASICON type oxides may be formed from LiMM' (PO) 4 ) 3 Where M and M' are independently selected from Al, ge, ti, sn, hf, zr, and La. For example, in certain variations, the one or more NASICON-type oxides may be selected from the group consisting of: li 1+x Al x Ge 2-x (PO 4 ) 3 (LAGP) (wherein x is 0. Ltoreq. X.ltoreq.2), li 1+x Al x Ti 2-x (PO 4 ) 3 (LATP) (where 0. Ltoreq. X. Ltoreq.2), li 1+x Y x Zr 2-x (PO 4 ) 3 (LYZP) (where x is 0. Ltoreq. X.ltoreq.2), li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 、LiTi 2 (PO 4 ) 3 、LiGeTi(PO 4 ) 3 、LiGe 2 (PO 4 ) 3 、LiHf 2 (PO 4 ) 3 And combinations thereof. The one or more perovskite-type ceramics may be selected from the group comprising: li 3.3 La 0.53 TiO 3 、LiSr 1.65 Zr 1.3 Ta 1.7 O 9 、Li 2x-y Sr 1-x Ta y Zr 1-y O 3 (where x =0.75y and 0.60 < y < 0.75), li 3/8 Sr 7/16 Nb 3/4 Zr 1/4 O 3 、Li 3x La (2/3-x) TiO 3 (where 0 < x < 0.25), and combinations thereof. In one variation, one or more of the oxide-based materials can have a thickness of greater than or equal to about 10 -5 S/cm to less than or equal to about 10 - 1 Ion conductivity of S/cm.
In various aspects, the sulfide-based particles may include one or more sulfide-based materials selected from the group consisting of: li 2 S-P 2 S 5 、Li 2 S-P 2 S 5 -MS x (wherein M is Si, ge and Sn and 0. Ltoreq. X. Ltoreq.2), li 3.4 Si 0.4 P 0.6 S 4 、Li 10 GeP 2 S 11.7 O 0.3 、Li 9.6 P 3 S 12 、Li 7 P 3 S 11 、Li 9 P 3 S 9 O 3 、Li 10.35 Si 1.35 P 1.65 S 12 、Li 9.81 Sn 0.81 P 2.19 S 12 、Li 10 (Si 0.5 Ge 0.5 )P 2 S 12 、Li(Ge 0.5 Sn 0.5 )P 2 S 12 、Li(Si 0.5 Sn 05 )PsS 12 、Li 10 GeP 2 S 12 (LGPS)、Li 6 PS 5 X (where X is Cl, br or I), li 7 P 2 S 8 I、Li 10.35 Ge 1.35 P 1.65 S 12 、Li 3.25 Ge 0.25 P 0.75 S 4 、Li 10 SnP 2 S 12 、Li 10 SiP 2 S 12 、Li 9.54 Si 1.74 P 1.44 S 11.7 C 10.3 、 (1-x) P 2 S 5-x Li 2 S (wherein 0.5. Ltoreq. X. Ltoreq.0.7) and combinations thereof. In one variation, the one or more sulfide-based materials can have a composition of greater than or equal to about 10 -7 An ionic conductivity of S/cm to less than or equal to about 1S/cm.
In various aspects, the halide-based particles can include one or more halide-based materials selected from the group consisting of: li 2 CdC l4 、Li 2 MgC 14 、Li 2 Cd I4 、Li 2 ZnI 4 、Li 3 OCl、LiI、Li 5 ZuI 4 、Li 3 OCl 1-x Br x (where 0 < x < 1), and combinations thereof. In one variation, the one or more halide-based materials can have a composition of greater than or equal to about 10 -8 S/cm to less than or equal to about 10 -1 Ion conductivity of S/cm.
In various aspects, the borate-based particles may comprise one or more borate-based materials selected from the group comprising: li 2 B 4 O 7 、Li 2 O-(B 2 O 3 )-(P 2 O 5 ) And combinations thereof. In one variation, the one or more borate-based materials may have a thickness of greater than or equal to about 10 -7 S/cm to less than or equal to about 10 -2 Ion conductivity of S/cm.
In various aspects, the nitride-based particles may include one or more nitride-based materials selected from the group consisting of: li 3 N、Li 7 PN 4 、LiSi 2 N 3 LiPON, and combinations thereof. In one variation, the one or more nitride-based materials may have a thickness of greater than or equal to about 10 -9 An ionic conductivity of S/cm to less than or equal to about 1S/cm.
In various aspects, the hydride-based particles can include one or more hydride-based materials from the group of: li 3 AlH 6 、LiBH 4 、LiBH 4 LiX (where X is one of Cl, br and I), liNH 2 、Li 2 NH、LiBH 4 -LiNH 2 And combinations thereof. In one variation, the one or more hydride-based materials can have a thickness of greater than or equal to about 10 -7 S/cm to less than or equal to about 10 -2 Ion conductivity of S/cm.
In further variations, the solid electrolyte particles may be one or more metal oxide particles or lithium-containing compounds, including but not limited to Al 2 O 3 、SiO 2 、TiO 2 、LiNbO 3 、Li 4 Ti 5 O 4 、Li 3 PO 4 。
In one embodiment, the solid electrolyte further comprises a portion of a polymer solid electrolyte, and the polymer solid electrolyte and the inorganic solid electrolyte form a composite solid electrolyte. In the embodiment of the application, the mass ratio of the inorganic solid electrolyte to the polymer solid electrolyte in the composite solid electrolyte has no special requirement, and a user can design according to actual needs. Wherein, the polymer solid electrolyte can be at least one of polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA) and polyethylene oxide (PEO).
In another embodiment, the solid electrolyte paste includes at least one of a binder and a lithium salt. The binder includes, but is not limited to, polyethylene glycol, polyethylene oxide (PEO), poly (p-phenylene oxide) (PPO), poly (methyl methacrylate) (PMMA), polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP), polyvinyl chloride (PVC), and combinations thereof, and the like, and may be selected according to actual needs without departing from the inventive concept of the present application, and is not specifically limited herein.
The lithium salt includes lithium hexafluorophosphate (LiPF) 6 ) Lithium perchlorate (LiClO) 4 ) Lithium aluminum tetrachloride (LiAlCl) 4 ) Lithium iodide (LiI), lithium bromide (LiBr), lithium thiocyanate (LiSCN), lithium tetrafluoroborate (LiBF) 4 ) Lithium difluoroborate (LiBF) 2 (C 2 O 4 ) (LiODFB), lithium tetraphenylborate (LiB (C)) 6 H 5 ) 4 ) Lithium bis (oxalato) borate (LiB (C) 2 O 4 ) 2 ) (LiBOB) and lithium tetrafluoro oxalate phosphate (LiPF) 4 (C 2 O 4 ) (LiFOP), lithium nitrate (LiNO) 3 ) Lithium hexafluoroarsenate (LiAsF) 6 ) Lithium trifluoromethanesulfonate (LiCF) 3 SO 3 ) Bis (trifluoromethanesulfonylimide) Lithium (LITFSI) (LiN (CF) 3 SO 2 ) 2 ) Lithium bis (fluorosulfonylimide) (LiN (FSO) 2 ) 2 ) (LIFSI) and combinations thereof. In certain variations, the lithium salt is selected fromFrom lithium hexafluorophosphate (LiPF) 6 ) Bis (trifluoromethanesulfonylimide) Lithium (LiTFSI) (LiN (CF) 3 SO 2 ) 2 ) Lithium bis (fluorosulfonylimide) (LiN (FSO) 2 ) 2 ) (LiFSI), fluoroalkyl lithium phosphonate (LiFAP), lithium phosphate (Li) 3 PO 4 ) And combinations thereof.
The type of the separator in the present application is not particularly limited, and may be any material used in the existing separator, such as PP film, PE/PP double-layer film, PE/PP/PE three-layer film, PP/PE/PP three-layer film, etc., without departing from the inventive concept of the present application.
S2: and (3) enabling one side of the composite diaphragm coated with the solid electrolyte slurry to be opposite to a pole piece to be processed, and rolling to transfer the solid electrolyte on the composite diaphragm to the surface of the pole piece to be processed to form a solid electrolyte layer so as to prepare and form the target pole piece.
Furthermore, both sides of the pole piece to be processed are covered with solid electrolyte layers. The pole piece to be treated comprises a current collector and an active substance layer coated on the surface of the current collector.
And the solid electrolyte on the composite diaphragm is transferred to two sides of the pole piece to be treated in a rolling manner. The rolling process in the embodiment of the application is realized by the preparation equipment of the pole piece. The preparation equipment of the pole piece is used for preparing the pole piece containing the solid electrolyte layer.
Fig. 2 is a schematic structural diagram of a device for manufacturing a pole piece according to an embodiment of the present application. As shown in fig. 2, the apparatus for preparing a pole piece includes a first unwinding shaft 11, a second unwinding shaft 12, a third unwinding shaft 13, a first hot-pressing roller 21, a second hot-pressing roller 22, a first winding shaft 31, a second winding shaft 32, and a third winding shaft 33. The first unwinding shaft 11 and the third unwinding shaft 13 are used for winding and drawing a first composite diaphragm and a second composite diaphragm, the second unwinding shaft 12 is arranged between the first unwinding shaft 11 and the third unwinding shaft 13, and the second unwinding shaft 12 is used for winding and drawing a pole piece to be processed. The first composite separator is composed of a first separator 40 and a first solid electrolyte layer 20 covering the surface of the first separator 40, and the second composite separator is composed of a second separator 50 and a second solid electrolyte layer 30 covering the surface of the second separator 50. The first and second heat and pressure rollers 21 and 22 are used to transfer the solid electrolyte layers on the first and second composite separators to the electrode sheet to be treated. The first winding shaft 31 and the third winding shaft 33 are used for recycling the first composite membrane and the second composite membrane, the second winding shaft 32 is arranged between the first winding shaft 31 and the third winding shaft 33, and the second winding shaft 32 is used for winding and winding the target pole piece coated with the solid electrolyte layer. The solid electrolyte layers on the first composite separator and the second composite separator in the embodiment of the present application may be the same or different, and are not limited herein.
In specific implementation, the first composite diaphragm, the pole piece to be processed and the second composite diaphragm are respectively drawn between the first hot-pressing roller 21 and the second hot-pressing roller 22 by the first unwinding shaft 11, the second unwinding shaft 12 and the third unwinding shaft 13 for rolling. Specifically, the pole piece to be processed is arranged between the first composite diaphragm and the second composite diaphragm, and the first composite diaphragm, the second composite diaphragm and the pole piece to be processed are bonded together in the hot pressing process. Further, a gap for two composite diaphragms and pole pieces to be processed to pass through is arranged between the first hot pressing roller 21 and the second hot pressing roller 22, and the gap between the first hot pressing roller 21 and the second hot pressing roller 22 is smaller than the sum of the thicknesses of the composite diaphragms and the pole pieces to be processed, so that the pressures of the first hot pressing roller 21 and the second hot pressing roller 22 can be applied to the composite diaphragms and the pole pieces to be processed. The gap between the first hot-pressing roller 21 and the second hot-pressing roller 22 is smaller than the sum of the thicknesses of the composite diaphragm and the pole piece to be processed, so that the solid electrolyte layer on the composite diaphragm can be coated on the pole piece to be processed, and the warped edge and the collapsed edge on the pole piece to be processed can be gradually leveled, so that the pole piece to be processed is more smooth. Preferably, the first hot-pressing roller 21 and the second hot-pressing roller 22 also have a heating function, and the composite separator and the pole piece to be processed can be heated during the rolling process, in the embodiment of the present application, the hot-pressing temperature is 80-110 ℃, specifically, the hot-pressing temperature may be 80, 90, 100 or 110 ℃, and a specific point value between the above point values, preferably 90-100 ℃, and for reasons of brevity and conciseness, the present invention does not exhaustively enumerate the specific point values included in the range. Heating in the temperature range is beneficial to the full volatilization of the solvent, and the bending and deformation of the pole piece are avoided. Further, the above coating speed is 5 to 30m/min, specifically, the coating speed may be 5, 10, 15, 20, 25 or 30m/min, and the specific point values therebetween are limited to space and for the sake of brevity, and the present invention is not intended to be exhaustive of the specific point values included in the range.
Fig. 3 is a schematic structural diagram of an intermediate product in a hot-pressing process, as shown in fig. 3, in the hot-pressing process, the first separator 40, the first solid electrolyte layer 20, the electrode sheet to be processed 10, the second solid electrolyte layer 30, and the second separator 50 are sequentially combined together. The intermediate product passes through between the first hot-pressing roller 21 and the second hot-pressing roller 22 under the traction of the first winding shaft 31, the second winding shaft 32 and the third winding shaft 33, and because the stripping force between the diaphragm layer and the solid electrolyte layer of the composite diaphragm is moderate, the diaphragm layer and the solid electrolyte layer of the composite diaphragm are stripped in the moving process, and the solid electrolyte layer of the composite diaphragm is transferred to the pole piece 10 to be processed.
Fig. 4 is a schematic structural diagram of a target pole piece coated with a solid electrolyte layer, and as shown in fig. 4, the target pole piece includes a pole piece 10 to be processed, and a first solid electrolyte layer 20 and a second solid electrolyte layer 30 coated on the surface of the pole piece 10 to be processed. Generally, a thicker solid electrolyte layer helps to improve the safety performance of the battery, and when the solid electrolyte is coated, the coating process is simple, but the thicker solid electrolyte layer affects the energy density of the battery and does not meet the requirements of light weight and thinness of the current battery. In the embodiments of the present application, the thickness of the solid electrolyte layer is 1 to 20 micrometers, specifically, the thickness of the solid electrolyte layer may be 1, 2, 3, 4, 5, 7, 10, 13, 16 or 20 micrometers, and specific values between the above values, preferably 2 to 6 micrometers, are included, but not exhaustive, and for brevity and conciseness.
A thinner solid electrolyte layer is advantageous in increasing the energy density of the battery and achieving lightness and thinness of the battery.
The application also provides a positive pole piece, and the positive pole piece is prepared by the preparation method of the pole piece. Further, the positive pole piece comprises a positive pole current collector, a positive pole active material layer covering the surface of the positive pole current collector, and a solid electrolyte layer covering the surface of the positive pole active material layer. The relevant contents of the solid electrolyte layer can be referred to the above description, and are not repeated here.
The positive electrode active material layer includes a positive electrode active material, and the positive electrode active material may be formed of a plurality of positive electrode active particles including one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. In some embodiments, the positive electrode active material layer further includes an electrolyte, such as a plurality of electrolyte particles.
The positive electrode active material may be one of a layered oxide, spinel, and polyanion. For example, the layered oxide (e.g., rock salt layered oxide) comprises one or more lithium-based positive electrode active materials selected from the group consisting of: liCoO 2 ，LiNi x Mn y Co 1-x-y O 2 (wherein x is 0. Ltoreq. X.ltoreq.1 and y is 0. Ltoreq. Y.ltoreq.1), liNi 1-x-y Co x Al y O 2 (where x is 0. Ltoreq. X.ltoreq.1 and y is 0. Ltoreq. Y.ltoreq.1), liNi x Mn 1-x O 2 (wherein 0. Ltoreq. X. Ltoreq.1) and Li 1+x MO 2 (wherein M is one of Mn, ni, co and Al and 0. Ltoreq. X. Ltoreq.1).
In one embodiment, one or more lithium-based positive electrode active materials may be optionally coated and/or may be doped. In addition, in certain embodiments, one or more lithium-based positive electrode active materials may optionally be mixed with one or more conductive materials that provide an electron conduction path and/or at least one polymeric binder material that improves the structural integrity of the positive electrode. For example, the positive electrode active material layer may include one or more lithium-based positive electrode active materials in an amount of greater than or equal to about 30wt% to less than or equal to about 98 wt%; greater than or equal to about 0wt% to less than or equal to about 30wt% of a conductive material; and greater than or equal to about 0wt% to less than or equal to about 20wt% binder, and in certain aspects, optionally greater than or equal to about 1wt% to less than or equal to about 20wt% binder.
As a preferred embodiment, in the examples of the present application, the positive electrode active material layer may be optionally mixed with a binder as follows: such as Polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile Butadiene Rubber (NBR), styrene-ethylene-butylene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof. The conductive material may include a carbon-based material, powdered nickel or other metal particles, or a conductive polymer. The carbon-based material may include particles such as carbon black, graphite, acetylene black (e.g., KETCHEN black or DENKATM black), carbon fibers and nanotubes, graphene, and the like. Examples of the conductive polymer include polyaniline, polythiophene, polyacetylene, polypyrrole, and the like.
The application also provides a lithium ion battery, lithium ion battery includes foretell positive pole piece, negative pole piece and diaphragm, the diaphragm set up in positive pole piece with between the negative pole piece. The relevant content of the positive electrode piece can be introduced with reference to the above description, and is not repeated here.
The negative pole piece comprises a negative pole current collector and a negative pole active substance layer formed on the negative pole current collector. The negative electrode current collector is not particularly limited as long as it has conductivity without causing chemical changes in the battery. Specifically, the negative electrode current collector includes, but is not limited to, elemental aluminum, copper, nickel, or zinc, for example, the negative electrode current collector may include elemental copper, such as copper foil.
Further, the anode active material layer includes an anode binder, an anode active material, and an anode conductive agent. The negative electrode binder includes, but is not limited to, polytetrafluoroethylene (PTFE), sodium carboxymethylcellulose (CMC), styrene Butadiene Rubber (SBR), polyvinylidene fluoride (PVDF), nitrile Butadiene Rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and the like. The negative active material includes at least one of graphite, soft carbon, hard carbon, silicon oxygen, or silicon carbon. The negative electrode conductive agent comprises at least one of conductive carbon black, carbon nanotubes, vapor grown carbon nanotubes or carbon nanofibers.
Hereinafter, embodiments of the present invention will be described more specifically by examples. However, the embodiments of the present invention are not limited to only these examples.
Example one
Coating the solid electrolyte slurry on a PP diaphragm to prepare and form a composite diaphragm, wherein the solid electrolyte slurry is a slurry formed by dissolving LLZO solid electrolyte in a solvent NMP;
the composite diaphragm coated with the solid electrolyte layer obtained by the preparation method is subjected to first unwinding and third unwinding, then enters the first hot-pressing roller and the second hot-pressing roller together with the positive pole piece to be processed from the second unwinding and the composite, and the composite positive pole piece is wound through the second winding shaft. At the moment, the solid electrolyte layer in the original composite diaphragm is compounded to the two sides of the positive pole piece to be processed, and the diaphragm in the composite diaphragm is recovered from the first winding shaft and the third winding shaft.
The current collector of the positive pole piece to be processed is aluminum foil, the positive active material layer is 96wt% of NCM622, the positive conductive agent is 2wt% of super-P, and the positive adhesive is 2wt% of PTFE.
The coating speed of this example was 15m/min and the hot pressing temperature was 90 ℃.
The thickness of the solid electrolyte layer on the surface of the finally prepared positive pole piece is 3 microns, and the solid electrolyte layer is free of curling and bending phenomena.
Example two
The difference between the second embodiment and the first embodiment is that the solid electrolyte slurry is SiO 2 A slurry of inorganic particles and a binder of PTFE dissolved in NMP as a solvent, wherein PTFE is in contact with LiNbO 3 The mass ratio of (A) to (B) is 9: 1. In addition, the hot pressing temperature in this example was 100 ℃.
The thickness of the solid electrolyte layer on the surface of the finally prepared positive pole piece is 2 microns, and the phenomena of curling and bending are avoided.
EXAMPLE III
The difference between the third embodiment and the first embodiment is that the solid electrolyte slurry is LiNbO 3 Inorganic solid electrolyte particles, PTFE binder, PEO polymer solid electrolyte, lithium hexafluorophosphate (LiPF) 6 ) A slurry of PTFE or LiNbO dissolved in NMP as a solvent 3 、PEO、LiPF 6 The mass ratio of (A) to (B) is 5: 0.5: 3.5: 1. In addition, the hot pressing temperature in this example was 110 ℃.
The thickness of the solid electrolyte layer on the surface of the finally prepared positive pole piece is 2.5 microns, and the phenomena of curling and bending are avoided.
In view of the above, the embodiment of the application provides a preparation method of a pole piece, a positive pole piece and a lithium ion battery. In the hot pressing process, the pole piece is in a tight state and is heated to promote the solvent to be fully volatilized, so that the pole piece is prevented from being curled and bent when being coated with the solid electrolyte.
The preparation method of the pole piece, the positive pole piece and the lithium ion battery provided by the application are introduced in detail, specific examples are applied in the description to explain the principle and the implementation mode of the application, and the description of the examples is only used for helping to understand the method and the core idea of the application; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific embodiments and the application range may be changed. In view of the above, the description should not be taken as limiting the application.
Claims (10)
1. A preparation method of a pole piece is characterized by comprising the following steps:
coating the solid electrolyte slurry on a diaphragm to prepare and form a composite diaphragm;
and the side, coated with the solid electrolyte slurry, of the composite diaphragm is opposite to a pole piece to be treated, and the solid electrolyte on the composite diaphragm is transferred to the surface of the pole piece to be treated by hot pressing to form a solid electrolyte layer so as to prepare a target pole piece.
2. The method for preparing the pole piece according to claim 1, wherein both sides of the pole piece to be treated are covered with a solid electrolyte layer.
3. The method for preparing the pole piece according to claim 2, wherein the solid electrolyte on the composite diaphragm is transferred to two sides of the pole piece to be treated in a rolling manner.
4. The method for manufacturing a pole piece according to claim 1, wherein the solid electrolyte paste comprises a solid electrolyte, and the solid electrolyte comprises an inorganic solid electrolyte.
5. The method of claim 4, wherein the solid electrolyte further comprises a polymer solid electrolyte.
6. The method for preparing the pole piece according to claim 4, wherein the solid electrolyte slurry further comprises at least one of a binder and a lithium salt.
7. The method for preparing the electrode sheet according to claim 1, wherein the thickness of the solid electrolyte layer is 1 to 20 μm.
8. The method for preparing the pole piece according to claim 1, wherein the hot pressing temperature is 80-110 ℃.
9. A positive pole piece, characterized in that, the positive pole piece is prepared according to the preparation method of any one of claims 1 to 8.
10. A lithium ion battery comprising the positive electrode sheet of claim 9, a negative electrode sheet, and a separator disposed between the positive electrode sheet and the negative electrode sheet.
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| CN202211442640.9A CN115714164A (en) | 2022-11-17 | 2022-11-17 | Preparation method of pole piece, positive pole piece and lithium ion battery |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116525753A (en) * | 2023-06-27 | 2023-08-01 | 苏州清陶新能源科技有限公司 | Preparation method and preparation device of composite pole piece and lithium ion battery |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116525753A (en) * | 2023-06-27 | 2023-08-01 | 苏州清陶新能源科技有限公司 | Preparation method and preparation device of composite pole piece and lithium ion battery |
| CN116525753B (en) * | 2023-06-27 | 2023-10-13 | 苏州清陶新能源科技有限公司 | Preparation method and preparation device of composite pole piece and lithium ion battery |
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