WO2018001164A1 - 电芯以及使用此电芯的电池 - Google Patents

电芯以及使用此电芯的电池 Download PDF

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Publication number
WO2018001164A1
WO2018001164A1 PCT/CN2017/089536 CN2017089536W WO2018001164A1 WO 2018001164 A1 WO2018001164 A1 WO 2018001164A1 CN 2017089536 W CN2017089536 W CN 2017089536W WO 2018001164 A1 WO2018001164 A1 WO 2018001164A1
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Prior art keywords
current collector
battery
battery cell
hole
cell according
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PCT/CN2017/089536
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English (en)
French (fr)
Inventor
金海族
许虎
Original Assignee
宁德时代新能源科技股份有限公司
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Application filed by 宁德时代新能源科技股份有限公司 filed Critical 宁德时代新能源科技股份有限公司
Priority to CN201780012785.6A priority Critical patent/CN108713271B/zh
Publication of WO2018001164A1 publication Critical patent/WO2018001164A1/zh
Priority to US16/212,446 priority patent/US10741818B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/536—Electrode connections inside a battery casing characterised by the method of fixing the leads to the electrodes, e.g. by welding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/531—Electrode connections inside a battery casing
    • H01M50/538—Connection of several leads or tabs of wound or folded electrode stacks
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • 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

Definitions

  • the invention belongs to the technical field of batteries, and particularly relates to an electric core with good electrolyte infiltration effect and a battery using the same.
  • Lithium-ion batteries have been widely used in new energy fields due to their high energy density, no memory effect, environmental protection and no pollution.
  • major companies have continuously explored and improved the performance and manufacturing process of power lithium-ion batteries.
  • the battery core As the core component of the battery, the battery core is usually assembled by lamination and winding. Among them, the winding method is adopted by the majority of battery manufacturers because of its advantages of simple process, high assembly efficiency, and easy automation.
  • a whitening current collector is usually left on both the positive electrode tab and the negative electrode tab. After the electric core is wound and formed, the white current collector is used for soldering the tab or the adapter piece.
  • the battery of the above structure has at least the following two problems: first, the whitening current collector not welded to the tab or the adapter piece is easily folded during the assembly process to hinder the electrolyte transport passage; second, it exists in The soldering of the tab or the adapter and the whitening fluid collector seals the passage of the electrolyte in the region through the gap between the pole pieces into the interior of the cell.
  • the present invention provides a battery core including
  • the positive and negative pole pieces are respectively provided with a white current collector, and the white current collectors of the positive and negative pole pieces are respectively welded with conductive sheets for connecting with external circuits; the blanks of the positive electrode pieces and/or the negative electrode pieces are respectively
  • the fluid collection channel is punched and cut;
  • the die cutting method of the electrolyte transmission channel includes one or two of the following: one is to punch out the semi-closed channel in the edge region of the white current collector which is not aligned with the conductive sheet, It is a completely closed channel that is punched out in the white current collector.
  • the present invention provides a battery including a battery case, a battery core, and an electrolyte, the battery core and the electrolyte solution being packaged in a battery case, the battery core being the present invention
  • the battery of the first aspect is the battery of the first aspect.
  • the present invention provides a battery cell comprising a positive electrode tab and a negative pole tab each provided with a white current collector, a white current collector and a negative pole tab of the positive pole tab
  • Each of the whitening current collectors is welded with a conductive sheet, and the white current collector of the positive electrode tab and the white current collector of the negative electrode tab each form a soldering mark at a portion welded to the conductive sheet;
  • the white current collector and the negative electrode of the positive electrode tab At least one of the whitening current collectors of the pole piece is provided with a hole-shaped fully enclosed passage formed by penetrating the white current collector in the thickness direction, and the fully enclosed passage is located on the inner side of the weld printing in the longitudinal direction; and/or
  • At least one of the whitening current collector of the positive electrode tab and the whitening current collector of the negative electrode tab is provided with a semi-closed passage formed by penetrating a corner portion of the white current collector in the thickness direction, and the semi-
  • the present invention provides a battery including a battery case, a battery core, and an electrolyte, and the battery core and the electrolyte are both enclosed in a battery case, and the battery core is according to the present invention.
  • the battery of the third aspect of the invention is according to the present invention.
  • the battery cell of the present invention improves the infiltration speed of the electrolyte by providing a fully enclosed channel and/or a semi-closed channel, while improving the rate and cycle life of the battery.
  • FIG. 1A is a schematic structural view of a battery cell according to Embodiment 1 of the present invention.
  • FIG. 1B is a perspective view of FIG. 1A.
  • FIG. 1C is an enlarged schematic view of a portion of the dashed box of FIG. 1B.
  • FIG. 2A is a schematic structural view of a battery cell according to Embodiment 2 of the present invention.
  • FIG. 2B is a perspective view of FIG. 2A.
  • FIG. 3A is a schematic structural view of a battery cell according to Embodiment 3 of the present invention.
  • FIG. 3B is a perspective view of FIG. 3A.
  • FIG. 4A is a schematic structural view of a battery cell according to Embodiment 4 of the present invention.
  • FIG. 4B is a perspective view of FIG. 4A.
  • FIG. 5A is a schematic structural view of a battery cell according to Embodiment 5 of the present invention.
  • FIG. 5B is a perspective view of FIG. 5A.
  • FIG. 6A is a schematic structural view of a battery cell according to Embodiment 6 of the present invention.
  • FIG. 6B is a perspective view of FIG. 6A.
  • FIG. 7A is a schematic structural view of a battery cell according to Embodiment 7 of the present invention.
  • FIG. 7B is a perspective view of FIG. 7A.
  • Fig. 8A is a schematic structural view of a battery cell of Comparative Example 1 of the present invention.
  • FIG. 8B is a perspective view of FIG. 8A.
  • Fig. 9 is a schematic structural view of a battery cell according to Embodiment 8 of the present invention.
  • Figure 10 is a schematic view showing the structure of a battery cell of Comparative Example 2 of the present invention.
  • the whitening current collector 10 of the positive electrode tab is a portion of the positive electrode current collector 51 of the positive electrode tab 5 where the positive electrode active material layer 52 is not provided on both surfaces; likewise, the white current collector 10 of the negative electrode tab is a negative electrode a portion of the negative electrode current collector 61 of the pole piece 6 on which no negative electrode active material layer 62 is provided on both surfaces; a white current collector of the positive electrode tab and a white current collector of the negative electrode tab are denoted by reference numeral 10;
  • the number of layers of the whitening current collector is not limited and may be selected depending on, for example, the energy density of the cell and the thickness.
  • Weld printing refers to the portion where the white current collector 10 and the corresponding conductive sheet are combined with the white current collector 10 and the conductive sheet when welding, and the adjacent two layers of the white current collector 10 are also bonded after welding. together.
  • a fully enclosed channel means that the projection in a plane perpendicular to the thickness direction is closed, the semi-closed channel is relative to a fully enclosed channel, and does not refer to a closed half, ie the semi-closed channel refers to being perpendicular to the thickness The projection in the plane of the direction is non-closed.
  • the extension of the width direction side surface S of the conductive sheet (the conductive sheet is a tab in FIGS.
  • the edge region of the white current collector that is not aligned with the conductive sheet (indicated by reference numeral 14, the edge region may also be referred to as an easy-to-break region).
  • the tabs are indicated by reference numeral 12 and the tabs are indicated by reference numeral 32, whereby the corresponding solder print corresponding to the tab 12 is indicated by reference numeral 16 and The weld mark corresponding to the adapter piece 32 is indicated by reference numeral 18.
  • the whitened current collector after winding has an approximately rectangular structure, and the corner portion refers to a right-angled region of the whitening current collector away from the active material layer region (ie, the core body portion 3).
  • the corner portion is an area surrounded by two broken lines in each of the upper left, upper right, lower left, and lower right areas.
  • the first aspect of the invention includes a positive and a negative pole piece respectively provided with a white current collector, and the white current collectors of the positive and negative pole pieces are respectively soldered with a conductive sheet for connecting with an external circuit; the positive electrode piece And / or the blank collector of the negative pole piece is punched with an electrolyte transport channel; the die cutting mode of the electrolyte transport channel includes one or two of the following, one is at the edge of the white current collector that is not aligned with the conductive sheet The region 14 is punched out of the semi-closed passage 4, and the second is a punched, fully closed passage on the white current collector.
  • the battery core improves the infiltration speed of the electrolyte while increasing the rate of the battery by punching the electrolyte transfer passage on the white current collector. And cycle life.
  • the fully enclosed passage is closer to the active material region of the battery core (ie, the core body portion 3) than the semi-closed passage 4, the path of the electrolyte into the active material region can be shortened, that is, the electrolyte is easier. Infiltrating with the active substance in the active substance region.
  • the semi-closed passage 4 is a right-angled passage formed by punching off all or part of the edge region 14 of the white current collector which is not aligned with the conductive sheet (see FIGS. 4A and 4B).
  • the projection of the semi-closed passage 4 in a plane perpendicular to the thickness direction T is a right-angled shape, and the concave curved passage (as shown in FIGS. 1A, 1B, 2A, and 2B, that is, the semi-closed passage 4)
  • the projection in a plane perpendicular to the thickness direction T is a concave curved shape or a triangular channel (as shown in FIGS.
  • the projection in a plane perpendicular to the thickness direction T is trapezoidal and the oblique side of the trapezoid is a projection of the semi-closed channel 4 such that each edge region 14 that is not aligned with the conductive sheet forms a triangle).
  • the hole-shaped fully enclosed passage is a circular hole-like structure 22 (as shown in FIGS. 6A, 6B, and 9), that is, the hole-shaped fully enclosed passage is perpendicular to the thickness direction.
  • the projection in the plane of T is a circular shape, and the elliptical hole-like structure 20 (as shown in FIGS. 2A, 2B, 3A, 3B, 5A, and 5B), that is, the hole-shaped fully enclosed passage is perpendicular to the thickness.
  • the projection in the plane of the direction T is an elliptical shape, and the rectangular hole-like structure 24 (as shown in FIGS.
  • the area of the pore-shaped fully enclosed channel accounts for 2% to 10% of the area of the white current collector before punching.
  • the hole-shaped fully enclosed passage is a plurality of hole-like structures side by side (as shown in FIGS. 6A, 6B, and 9), that is, the hole-shaped fully enclosed passage is perpendicular to the thickness.
  • the projection in the plane of the direction T is a plurality of holes arranged side by side).
  • the hole-shaped fully enclosed passage is a rectangular hole-like structure (as shown in FIGS. 7A and 7B, that is, the hole-shaped fully enclosed passage is in a plane perpendicular to the thickness direction T
  • the projection is a rectangle) or an elliptical hole-like structure 20 (as shown in FIGS. 2A, 2B, 3A, 3B, 5A, and 5B), that is, the hole-shaped fully enclosed passage is perpendicular to the thickness direction T.
  • the projection in the plane is elliptical), and the long side of the rectangle or the long axis of the ellipse is parallel to the weld.
  • the conductive sheet is a positive and negative electrode 12, or a positive and negative electrode tab 32 connected to the battery top cover.
  • the battery core is a wound type electric core, and the electrolyte transmission passage on the white current collector is punched out before the electric core is wound, or in the electric core coil. After punching out; preferably after one-time punching out of the cell.
  • a battery according to a second aspect of the present invention includes a battery case, a battery cell, and an electrolyte, and the battery cell and the electrolyte are both enclosed in a battery case, the battery core being the battery core according to the first aspect of the invention.
  • the battery case is a soft package, the conductive piece is the positive and negative ear 12; or the battery case is a hard case package, and the conductive piece is connected to the battery cover 30.
  • Negative electrode transfer piece 32 is
  • the electric core of the third aspect of the invention comprises a positive electrode piece and a negative electrode piece each provided with a white current collector, and the white current collector of the positive electrode piece and the white current collector of the negative electrode piece are each welded with a conductive piece, and the positive electrode is
  • the whitening current collector of the sheet and the whitening current collector of the negative electrode tab each form a soldering mark at a portion welded to the conductive sheet; at least one of the white current collector of the positive electrode tab and the white current collector of the negative electrode tab is provided with a hole-shaped fully enclosed passage formed by penetrating the white current collector in the thickness direction T, and the fully closed channel position
  • the inner side of the solder print in the longitudinal direction L is as shown in FIGS.
  • At least one of the whitening current collector of the positive electrode tab and the whitening current collector of the negative electrode tab is provided with a semi-closed passage 4 formed by penetrating a corner portion of the white current collector in the thickness direction T, and the semi-closed passage 4 Located on one side of the solder print in the width direction W, as shown in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, and 4B.
  • the battery cell is provided with the fully enclosed passage and/or the semi-closed passage 4 by the whitening current collector, and the electrolyte is improved in the infiltration speed when the battery is applied to the battery, and is improved. Battery rate and cycle life.
  • the fully enclosed passage is closer to the active material region of the battery core (ie, the core body portion 3) than the semi-closed passage 4, the path of the electrolyte into the active material region can be shortened, that is, the electrolyte is easier. Infiltrating with the active substance in the active substance region.
  • the projection of the hole-shaped fully enclosed passage in a plane perpendicular to the thickness direction T is circular (as shown in FIG. 6A, FIG. 6B, FIG. 9 and indicated by reference numeral 22), and elliptical (FIG. 2A, 2B, 3A, 3B, 5A, 5B and indicated by reference numeral 20, rectangular (as shown in FIGS. 7A and 7B and indicated by reference numeral 24), triangle (not shown) Or trapezoidal (not shown).
  • the projection of the hole-shaped fully enclosed passage in a plane perpendicular to the thickness direction T is a plurality of holes arranged side by side (indicated by reference numeral 22). ).
  • the projection of the hole-shaped fully enclosed passage in a plane perpendicular to the thickness direction T is rectangular (as shown in FIGS. 7A and 7B and indicated by reference numeral 24) and the long side of the rectangle is parallel to the weld mark 16, or
  • the projection of the hole-shaped fully enclosed passage in a plane perpendicular to the thickness direction T is elliptical (as shown in FIGS.
  • the shape of the whitening current collector 10 can be sufficiently adapted and the size in the width direction W can be maximized, so that the range in which the electrolyte enters the active material region can be enhanced.
  • the hole-like fully enclosed passage can be formed by die cutting.
  • the area of the apertured fully enclosed channel accounts for 2% to 10% of the area of the white current collector prior to die cutting. This increases the rate of entry of the electrolyte while ensuring the strength of the white collector.
  • the battery cell is a wound type core, and the white current collector of the positive electrode tab and the white current collector of the negative electrode tab are along the length direction. Opposite The direction extends.
  • the projection of the semi-closed passage 4 in a plane perpendicular to the thickness direction T is a concave curved shape as shown in FIGS. 1A, 1B, 2A, and 2B.
  • the projection of the white current collector of the positive electrode tab and/or the white current collector of the negative electrode tab in a plane perpendicular to the thickness direction T is trapezoidal, as shown in FIGS. 3A and 3B. .
  • the hypotenuse of the trapezoid is now the projection of the semi-closed channel 4.
  • the semi-closed channel 4 adopts FIGS. 1A, 1B, 2A, and 2B.
  • the shape shown or the shape shown in Figures 3A and 3B ensures a greater flow area of the white trap.
  • the semi-closed passage 4 adopts the right-angled structure of FIG. 4A and FIG. 4B when the white-collecting fluid 10 is subjected to an external force, stress concentration and tearing are easily generated at a right angle, and when the semi-closed passage 4 adopts FIGS. 1A and 1B, In the shape shown in FIGS.
  • the whitening current collector 10 When the whitening current collector 10 is shape-cut before being wound by the electric core so that the wound-shaped electric core forms the semi-closed passage 4, it is semi-closed as compared with the semi-closed passage 4 of the right-angled structure of FIGS. 4A and 4B.
  • the shape of the channel 4 adopts the shape shown in FIG. 1A, FIG. 1B, FIG. 2A, FIG. 2B or the shape shown in FIG. 3A and FIG. 3B is enhanced by the large area of the whitening current collector left after the cutting, thereby making the bending resistance enhanced.
  • the whitening current collector after cutting and the conductive sheets (the tabs 12 or the tabs 32) are not easily folded.
  • the two conductive sheets are a positive electrode tab and a negative electrode tab, respectively, or two conductive sheets are respectively a positive electrode adapter piece and a negative electrode adapter piece connected to the battery top cover 30.
  • the positive electrode is directly formed by the white current collector of the positive electrode tab, and the negative electrode is directly formed by the white current collector of the negative electrode tab; the positive electrode tab is directly formed by the white current collector of the positive electrode tab, and the negative electrode is transferred.
  • the sheet is formed directly from the white current collector of the negative electrode tab.
  • the multilayer whitener current collector is laminated and ultrasonically welded together to form a tab or tab.
  • the multi-layered white current collectors can be laminated after ultrasonic welding and welding to meet the size requirements of the tabs or tabs.
  • a battery according to a fourth aspect of the present invention includes a battery case, a battery cell, and an electrolyte, both of which are housed in a battery case, the battery core being the battery cell according to the third aspect of the present invention.
  • positive electrode sheet positive electrode active material Li(Ni 1/3 Co 1/3 Mn 1/3 )O2, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) by mass ratio 97:2:1
  • NMP N-methyl-2-pyrrolidone
  • the positive electrode slurry was uniformly coated on a positive electrode current collector aluminum foil at 85 ° C After drying, cold pressing, slitting, to make the battery positive pole piece.
  • negative electrode tab The negative electrode active material graphite, conductive agent acetylene black, thickener sodium hydroxymethyl cellulose (CMC), binder styrene butadiene rubber (SBR) were mixed at a mass ratio of 96:2:1:1. Evenly, the battery negative electrode slurry was prepared; the negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, dried at 85 ° C, then cold pressed, and stripped to form a battery negative electrode piece.
  • CMC thickener sodium hydroxymethyl cellulose
  • SBR binder styrene butadiene rubber
  • Preparation of separator A 16 ⁇ m thick polyethylene microporous film was selected as the porous separator substrate.
  • the inorganic alumina powder, the polyvinylpyrrolidone, and the acetone solvent are uniformly mixed at a mass ratio of 3:1.5:5.5 to form a slurry, which is coated on one side of the porous separator substrate and dried.
  • the polyvinylidene fluoride powder, the acetone solvent, and the ethyl acetate are uniformly mixed at a mass ratio of 10:35:55 to form a slurry, and the porous separator substrate subjected to the inorganic coating surface treatment is subjected to a slurry. Double-coated, the two-sided organic coating has the same weight and thickness.
  • Lithium hexafluorophosphate is dissolved in a mixed solvent of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate (the volume ratio of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate is 1:2:1) , to get the required electrolyte.
  • the positive and negative pole pieces and the separator are formed into a battery core by winding, and the white current collectors of the positive and negative pole pieces are respectively located at both ends of the wound battery core, since the present invention does not relate to The polarities of the positive and negative electrodes are distinguished, so the positive and negative electrodes are no longer described differently in the following description.
  • the whitening current collector 10 of the positive and negative pole pieces is soldered with the tab 12 of corresponding polarity, and the cell is connected to the external circuit through the tab 12 of the two poles.
  • each of the easy-folding regions 14 on the whitening current collector 10 is punched off a portion of the arc, so that the easy-folding region 14 becomes a semi-closed concave curved channel, so that the electrolyte can be along the arrow in the figure.
  • the mode is transmitted to the positive and negative pole pieces.
  • the above-mentioned battery core is packaged, and after being injected, formed, and evacuated, a soft pack battery can be obtained.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • the present embodiment is not only the punched area 14 is punched into a concave curved channel but also behind the solder print 16 of the tab 12 ( Referring to the region between the solder print 16 and the core body portion 3, a blank trapped liquid structure 10 is punched out from the white current collector 10 of the following embodiment; the length of the elliptical hole-like structure 20 is The shaft is parallel to the weld mark 16 and its area accounts for 6% of the area of the white current collector 10 before punching to ensure overcurrent capability.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • the difference between the embodiment and the embodiment 1 is that the easy-to-break region 14 is not punched into a concave curved channel, but is punched into a semi-closed triangular channel.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • the difference between the embodiment and the embodiment 1 is that the easy-to-break region 14 is not punched into a concave curved channel, but the easy-to-break region 14 is completely cut off. Form a right angle channel.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • Embodiment 1 the difference between this embodiment and Embodiment 1 is only that the present embodiment does not punch the easy-folding region 14, but the whitening current collector behind the solder print 16 of the tab 12. 10 is punched out a fully enclosed elliptical hole-like structure 20; the long axis of the elliptical hole-like structure 20 is parallel to the weld mark 16, and its area accounts for 6% of the area of the white current collector 10 before punching to ensure Overcurrent capability.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • Embodiment 1 the difference between this embodiment and Embodiment 1 is only that the present embodiment does not punch the easy-folding region 14, but the whitening current collector behind the soldering film 16 of the tab 12. 10 is punched out a row of 4 fully enclosed circular hole-like structures 22; the sum of the areas of the circular hole-like structures 22 accounts for 2% of the area of the white current collector 10 before punching to ensure overcurrent capability.
  • This embodiment is identical to Embodiment 1 except for the punching method of the white current collector 10.
  • Embodiment 1 the difference between this embodiment and Embodiment 1 is only that the present embodiment does not punch the easy-folding region 14, but the whitening current collector behind the solder print 16 of the tab 12 is provided. 10 is punched out to form a fully enclosed rectangular hole-like structure 24; the long side of the rectangular hole-like structure 24 is parallel to the welding mark 16, and its area accounts for 10% of the area of the white current collector 10 before punching to ensure the overcurrent capability. .
  • the present comparative example is identical to that of Embodiment 1, except that the whitening current collector 10 is not die cut at the time of cell preparation, and all of the easily foldable regions 14 are retained.
  • the difference between this embodiment and the embodiment 1 is that, firstly, the battery of the embodiment is a hard-shell battery, and the tabs 12 of the positive and negative pole pieces are not soldered to the ear 12, but Directly connected with the positive and negative electrode tabs 32 connected to the battery top cover 30, and connected to the external circuit through the adapter piece 32; secondly, the blanking current collector 10 is punched in the soldering pattern 18 of the adapter piece 32. A row of four fully enclosed circular hole-like structures 22 is punched out at the rear; the sum of the areas of the circular hole-like structures 22 is occupied.
  • the white current collector has a 3% area of 10 to ensure overcurrent capability.
  • the positive electrode tab, the negative electrode tab, the separator, the electrolyte, and the like used in the present embodiment are completely the same as those in Embodiment 1, and are not described herein again.
  • the above-mentioned battery core is packaged, and after being injected, formed, and evacuated, a hard-shell battery can be obtained.
  • the present comparative example is identical to that of the embodiment 8, except that the whitening current collector 10 is not punched at the time of preparation of the cell, so that the whitening current collector 10 behind the soldering film 18 remains as it is.
  • the hole-shaped fully enclosed passage punched out on the white current collector behind the conductive sheet soldering such as the elliptical hole-like structure 20, the circular hole-shaped structure 22, and the rectangular hole.
  • the structure 24 and the like have a feature size of 1 to 10 mm.
  • Cyclic performance test The battery was circulated at 60 ° C, 2 C / 3 C for 800 weeks, and its capacity retention rate was examined.
  • the voltage range was 2.8 V to 4.2 V, and charging was performed at a magnification of 2 C, and discharge was performed at a magnification of 3 C.
  • the cycle capacity retention rate is a percentage of the 3C discharge capacity of the 800th cycle with respect to the second discharge capacity.
  • the battery cell of the present invention punches out the electrolyte channel through the whitening current collector in the easy-to-break region and/or the conductive sheet after the conductive white plate has sufficient overcurrent capability. On the one hand, it effectively prevents the easy-to-break area from being impaired and hinders the electrolyte transmission. On the other hand, it opens the electrolyte transmission channel sealed by the tab/tune plate, which greatly increases the infiltration speed of the electrolyte to the pole piece, and significantly reduces the rate. After the liquid injection, the static infiltration time of the battery core can also ensure the electrolyte retention inside the battery core at the end of the cycle, thereby effectively improving the cycle life of the battery core. In addition, the punching process of the battery of the present invention is simple, and therefore can be widely and rapidly applied in different batteries.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Secondary Cells (AREA)
  • Connection Of Batteries Or Terminals (AREA)
  • Cell Electrode Carriers And Collectors (AREA)
  • Engineering & Computer Science (AREA)
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Abstract

本发明公开了一种电芯以及使用此电芯的电池。所述电芯包括分别设有留白集流体的正负极极片，正负极极片的留白集流体分别焊接有用于与外界电路相连的导电片；所述正极极片和/或负极极片的留白集流体上冲切有电解液传输通道；电解液传输通道的冲切方式包括以下一种或两种，一是在留白集流体的留白集流体的与导电片不对齐的边缘区域冲切出半封闭通道，二是在留白集流体上冲切出孔状的全封闭通道。与现有技术相比，本发明电芯通过在留白集流体上冲切电解液传输通道，改善了电解液的浸润速度，同时提高了电池的倍率和循环寿命。

Description

电芯以及使用此电芯的电池 技术领域
本发明属于电池技术领域，尤其涉及一种电解液浸润效果好的电芯以及使用此电芯的电池。
背景技术
锂离子电池因具有能量密度大、无记忆效应、环保无污染等优点，已经在新能源领域得以广泛应用。在竞争激烈的新能源汽车市场中，各大公司都针对动力锂离子电池的性能和制造工艺进行了不断地探索和改进。电芯作为电池的核心部件，通常采用叠片和卷绕两种方式进行装配。其中，卷绕方式因具有工艺简单、装配效率高、易于自动化等优点，被广大电池制造企业所采用。
在电池卷绕工艺中，通常在正极极片和负极极片上均留有留白集流体，电芯卷绕成形后，留白集流体处用于焊接极耳或转接片。但是，上述结构的电芯至少存在以下两个问题：第一，未与极耳或转接片焊接的留白集流体很容易在装配过程中打折而阻碍电解液传输通道；第二，存在于极耳或转接片与留白集流体焊接处的焊印，封闭了该区域电解液通过极片间缝隙浸入电芯内部的通道。以上两个问题都对电芯的充分浸润不利，导致注液后的电芯所需静置时间增长；同时，电池极片有可能因电解液浸润不足而导致循环后期时析出锂枝晶。
有鉴于此，确有必要提供一种能够解决上述问题的电芯以及使用此电芯的电池。
发明内容
本发明的目的在于提供一种能够有效改善电解液浸润效果的电芯，以制备出具有较佳倍率性能和循环寿命的电池。
为了实现上述发明目的，在第一方面，本发明提供了一种电芯，其包括 分别设有留白集流体的正负极极片，正负极极片的留白集流体分别焊接有用于与外界电路相连的导电片；所述正极极片和/或负极极片的留白集流体上冲切有电解液传输通道；电解液传输通道的冲切方式包括以下一种或两种，一是在留白集流体的与导电片不对齐的边缘区域冲切出半封闭通道，二是在留白集流体上冲切出孔状的全封闭通道。
为了实现上述发明目的，在第二方面，本发明提供了一种电池，其包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内，所述电芯为本发明第一方面所述的电芯。
为了实现上述发明目的，在第三方面，本发明提供了一种电芯，其包括各设有留白集流体的正极极片和负极极片，正极极片的留白集流体和负极极片的留白集流体各焊接有导电片，正极极片的留白集流体和负极极片的留白集流体各在与导电片焊接的部位形成焊印；正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向贯通留白集流体而形成的孔状的全封闭通道，且全封闭通道位于焊印的沿长度方向的内侧；和/或，正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向贯通留白集流体的拐角部而形成的半封闭通道，且半封闭通道位于焊印的沿宽度方向的一侧。
为了实现上述发明目的，在第四方面，本发明提供了一种电池，其包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内，所述电芯为根据本发明第三方面所述的电芯。
与现有技术相比，本发明的电芯通过设置全封闭通道和/或半封闭通道，改善了电解液的浸润速度，同时提高了电池的倍率和循环寿命。
附图说明
下面结合附图和具体实施例，对本发明电芯、使用此电芯的电池及其有益效果进行详细说明。
图1A为本发明实施例1的电芯的结构示意图。
图1B为图1A的立体示意图。
图1C为图1B的虚框部分的放大示意图。
图2A为本发明实施例2的电芯的结构示意图。
图2B为图2A的立体示意图。
图3A为本发明实施例3的电芯的结构示意图。
图3B为图3A的立体示意图。
图4A为本发明实施例4的电芯的结构示意图。
图4B为图4A的立体示意图。
图5A为本发明实施例5的电芯的结构示意图。
图5B为图5A的立体示意图。
图6A为本发明实施例6的电芯的结构示意图。
图6B为图6A的立体示意图。
图7A为本发明实施例7的电芯的结构示意图。
图7B为图7A的立体示意图。
图8A为本发明对比例1的电芯的结构示意图。
图8B为图8A的立体示意图。
图9为本发明实施例8的电芯的结构示意图。
图10为本发明对比例2的电芯的结构示意图。
其中，附图标记说明如下：
10 留白集流体
12 极耳
14 边缘区域
16、18 焊印
20 椭圆形孔状结构
22 圆形孔状结构
24 矩形孔状结构
30 电池顶盖
32 转接片
3 电芯主体部
4 半封闭通道
5 正极极片
51 正极集流体
52 正极活性物质层
6 负极极片
61 负极集流体
62 负极活性物质层
7 隔离膜
S 宽度方向侧面
L 长度方向
W 宽度方向
T 厚度方向
具体实施方式
在详细说明之前，对本发明的内容做如下说明。正极极片的留白集流体10为正极极片5的正极集流体51的在两个表面上均未设置正极活性物质层52的部分；同样地，负极极片的留白集流体10为负极极片6的负极集流体61的在两个表面上均未设置负极活性物质层62的部分；正极极片的留白集流体和负极极片的留白集流体均用附图标记10标示；留白集流体的层数不受限制，可以依据例如电芯的能量密度以及厚度来选择。焊印指的是留白集流体10与对应的导电片在采用焊接时留白集流体10与导电片结合在一起的部位，在焊接后相邻的两层留白集流体10也会结合在一起。全封闭通道指的是在垂直于厚度方向的平面内的投影是封闭的，半封闭通道是相对全封闭通道而言的，并非指的是封闭一半，即半封闭通道指的是在垂直于厚度方向的平面内的投影是非封闭的。在图1B至图8B中，以虚线示出了导电片(在图1B至图8B中导电片为极耳)的宽度方向侧面S的延伸，沿宽度方向W位于各虚线侧方的区域为留白集流体的与导电片不对齐的边缘区域(用附图标记14表示，基于背景技术的说明，边缘区域也可称为易打折区域)。为了便于区分导电片的不同应用，极耳用附图标记12表示，而转接片用附图标记32表示，由此相应的与极耳12对应的焊印用附图标记16表示，而与转接片32对应的焊印用附图标记18表示。当未设置半封闭通道时，卷绕后的留白集流体呈近似长方形结构，拐角部指的是留白集流体的远离活性物质层区域(即电芯主体部3)的直角区域，以图8B和图9、图10为例，拐角部为左上、右上、左下、右下四个区域中的各区域以两条虚线围成的区域。 尽管本发明的附图以卷绕式电芯示例，但是不受此限制，本发明的技术构思同样适用于叠片式电芯或卷加叠电芯。
首先说明根据本发明第一方面的电芯。
本发明的第一方面电芯包括分别设有留白集流体的正负极极片，正负极极片的留白集流体分别焊接有用于与外界电路相连的导电片；所述正极极片和/或负极极片的留白集流体上冲切有电解液传输通道；电解液传输通道的冲切方式包括以下一种或两种，一是在留白集流体的与导电片不对齐的边缘区域14冲切出半封闭通道4，二是在留白集流体上冲切出孔状的全封闭通道。
在根据本发明的第一方面的电芯中，电芯通过在留白集流体上冲切电解液传输通道，在电芯应用于电池时，改善了电解液的浸润速度，同时提高了电池的倍率和循环寿命。此外，与半封闭通道4相比，全封闭通道由于整体上更靠近电芯的活性物质区域(即电芯主体部3)，所以能够缩短电解液进入活性物质区域的路径，即电解液更容易与活性物质区域的活性物质浸润。
作为本发明电芯的一种改进，所述半封闭通道4为将留白集流体的与导电片不对齐的边缘区域14全部或部分冲切掉而形成的直角通道(如图4A和图4B所示，即半封闭通道4在垂直于厚度方向T的平面内的投影为直角形)、内凹弧形通道(如图1A、图1B、图2A、图2B所示，即半封闭通道4在垂直于厚度方向T的平面内的投影为内凹弧形)或三角形通道(如图3A和图3B所示，即正极极片的留白集流体和/或负极极片的留白集流体在垂直于厚度方向T的平面内的投影为梯形且梯形的斜边为半封闭通道4的投影，从而与导电片不对齐的各边缘区域14形成三角形)。
作为本发明电芯的一种改进，所述孔状的全封闭通道为圆形孔状结构22(如图6A、图6B、图9所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为圆形)、椭圆形孔状结构20(如图2A、图2B、图3A、图3B、图5A、图5B所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为椭圆形)、矩形孔状结构24(如图7A和图7B所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为矩形)、三角形孔状结构(未示出，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为三角形)或梯形孔状结构(未示出，即孔状的全封闭通道在垂直于厚度方向T的平面 内的投影为梯形)。
作为本发明电芯的一种改进，所述孔状的全封闭通道的面积占冲切前留白集流体面积的2％～10％。
作为本发明电芯的一种改进，所述孔状的全封闭通道为并排的多个孔状结构(如图6A、图6B、图9所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为并排的多个孔)。
作为本发明电芯的一种改进，所述孔状的全封闭通道为一个长方形孔状结构(如图7A和图7B所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为长方形)或是一个椭圆形孔状结构20(如图2A、图2B、图3A、图3B、图5A、图5B所示，即孔状的全封闭通道在垂直于厚度方向T的平面内的投影为椭圆形)，长方形的长边或椭圆形的长轴与焊印平行。
作为本发明电芯的一种改进，所述导电片为正负极耳12，或与电池顶盖连接的正负极转接片32。
作为本发明电芯的一种改进，所述电芯为卷绕型电芯，其留白集流体上的电解液传输通道是在电芯卷绕前冲切出来的，或是在电芯卷绕后冲切出来的；优选为在电芯卷绕后一次性冲切出来。
其次说明根据本发明第二方面的电池。
根据本发明第二方面的电池包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内，所述电芯为本发明第一方面所述的电芯。
作为本发明电池的一种改进，所述电池壳体为软包封装袋，导电片为正负极耳12；或电池壳体为硬壳封装壳，导电片为与电池顶盖30连接的正负极转接片32。
接着说明根据本发明第三方面的电芯。
本发明第三方面的电芯包括各设有留白集流体的正极极片和负极极片，正极极片的留白集流体和负极极片的留白集流体各焊接有导电片，正极极片的留白集流体和负极极片的留白集流体各在与导电片焊接的部位形成焊印；正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向T贯通留白集流体而形成的孔状的全封闭通道，且全封闭通道位 于焊印的沿长度方向L的内侧，如图2A、图2B、图3A、图3B、图5A、图5B、图6A、图6B、图7A、图7B、图9所示；和/或，正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向T贯通留白集流体的拐角部而形成的半封闭通道4，且半封闭通道4位于焊印的沿宽度方向W的一侧，如图1A、图1B、图2A、图2B、图3A、图3B、图4A以及图4B所示。
在根据本发明第三方面的电芯中，电芯通过留白集流体设置全封闭通道和/或半封闭通道4，在电芯应用于电池时，改善了电解液的浸润速度，同时提高了电池的倍率和循环寿命。此外，与半封闭通道4相比，全封闭通道由于整体上更靠近电芯的活性物质区域(即电芯主体部3)，所以能够缩短电解液进入活性物质区域的路径，即电解液更容易与活性物质区域的活性物质浸润。
所述孔状的全封闭通道在垂直于厚度方向T的平面内的投影为圆形(如图6A、图6B、图9所示且由附图标记22标示)、椭圆形(如图2A、图2B、图3A、图3B、图5A、图5B所示且由附图标记20标示)、矩形(如图7A和图7B所示且由附图标记24标示)、三角形(未示出)或梯形(未示出)。
在一实施例中，如图6A、图6B、图9所示，所述孔状的全封闭通道在垂直于厚度方向T的平面内的投影为并排的多个孔(由附图标记22标示)。所述孔状的全封闭通道在垂直于厚度方向T的平面内的投影为长方形(如图7A和图7B所示且由附图标记24标示)且长方形的长边与焊印16平行，或者所述孔状的全封闭通道在垂直于厚度方向T的平面内的投影为椭圆形(如图2A、图2B、图3A、图3B、图5A、图5B所示且由附图标记20标示)且椭圆形的长轴与焊印16平行。由此可以充分地适应留白集流体10的形状并使得沿宽度方向W的尺寸最大化，从而能够增强电解液进入活性物质区域的范围。
在制造时，所述孔状的全封闭通道可通过冲切的方式形成。在一实施例中，所述孔状的全封闭通道的面积占冲切前留白集流体面积的2％～10％。由此一方面提高电解液进入的速度同时保证留白集流体的强度。
在一实施例中，如图1A至图7B以及图9所示，所述电芯为卷绕型电芯，正极极片的留白集流体和负极极片的留白集流体沿长度方向L分别朝相反的 方向延伸。
在一实施例中，所述半封闭通道4在在垂直于厚度方向T的平面内的投影为内凹弧形，如图1A、图1B、图2A、图2B所示。
在另一实施例中，所述正极极片的留白集流体和/或负极极片的留白集流体在垂直于厚度方向T的平面内的投影为梯形，如图3A和图3B所示。此时梯形的斜边为半封闭通道4的投影。
与图4A和图4B的直角结构的半封闭通道4(即在垂直于厚度方向T的平面内的投影为直角形)相比，半封闭通道4采用图1A、图1B、图2A、图2B所示的形状或图3A和图3B所示的形状，可以保证留白集流体有更大的过流面积。此外，当半封闭通道4采用图4A和图4B的直角结构时，留白集流体10受到外力时容易在直角处产生应力集中进而撕裂，而当半封闭通道4采用图1A、图1B、图2A、图2B所示的形状或图3A和图3B所示的形状时，由于不存在直角结构的90度的拐角，所有留白集流体不会存在直角结构的应力集中的问题。此外，与图4A和图4B的直角结构的半封闭通道4相比，当进一步设置全封闭通道(例如图2A、图2B、图3A和图3B的椭圆形)时，在保证留白集流体有更大的过流面积的同时还可以使得全封闭通道做得更大，从而电解液的浸润速度更快。当通过电芯卷绕之前对留白集流体10进行形状切割从而卷绕成型后的电芯形成半封闭通道4时，与图4A和图4B的直角结构的半封闭通道4相比，半封闭通道4采用图1A、图1B、图2A、图2B所示的形状或图3A和图3B所示的形状因切割后留下的留白集流体面积大而抗挠曲性增强，从而使得在卷绕过程中切割后的留白集流体以及导电片(极耳12或转接片32)不易翻折。
所述两个导电片分别为正极耳和负极耳或两个导电片分别为与电池顶盖30连接的正极转接片和负极转接片。
优选地，正极耳由正极极片的留白集流体直接形成，负极耳由负极极片的留白集流体直接形成；正极转接片由正极极片的留白集流体直接形成，负极转接片由负极极片的留白集流体直接形成。多层留白集流体层压并超声焊接焊接在一起，从而形成极耳或转接片。当然多层留白集流体层压并超声焊接焊接在一起之后可以进行切割，以满足极耳或转接片在尺寸上的需要。
最后说明根据本发明第四方面的电池。
根据本发明第四方面的电池包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内，所述电芯为根据本发明第三方面所述的电芯。
为了使本发明的目的、技术方案和有益技术效果更加清晰明白，以下结合附图和实施例以及对比例，对本发明进行进一步详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本发明，并不是为了限定本发明。
实施例1
正极极片的制备：将正极活性物质Li(Ni1/3Co1/3Mn1/3)O2、导电剂乙炔黑、粘结剂聚偏氟乙烯(PVDF)按质量比97：2：1混合均匀，并加入到作为溶剂的N-甲基-2-吡咯烷酮(NMP)中，制成具有一定粘度的正极浆料；将正极浆料均匀涂布在正极集流体铝箔上，在85℃下烘干后冷压，分条，做成电池正极极片。
负极极片的制备：将负极活性物质石墨、导电剂乙炔黑、增稠剂羟甲基纤维素钠(CMC)、粘结剂丁苯橡胶(SBR)按质量比96：2：1：1混合均匀，制成电池负极浆料；将负极浆料均匀涂布在负极集流体铜箔上，在85℃下烘干后进行冷压，分条，做成电池负极极片。
隔离膜的制备：选用16μm厚的聚乙烯微孔薄膜作为多孔隔离膜基材。将无机三氧化二铝粉末、聚乙烯呲咯烷酮、丙酮溶剂按质量比3：1.5：5.5混合均匀制成浆料，并涂布于多孔隔离膜基材的一面，烘干。然后，在此基础上，将聚偏氟乙烯粉末、丙酮溶剂、乙酸乙酯按质量比10：35：55混合均匀制成浆料，并对经过无机涂层表面处理的多孔隔离膜基材进行双面涂布，两面有机涂层的重量和厚度一致。
电解液的制备：将六氟磷酸锂溶解于碳酸乙烯酯、碳酸二甲酯及碳酸甲乙酯的混合溶剂中(碳酸乙烯酯、碳酸二甲酯、碳酸甲乙酯的体积比为1：2：1)，得到所需电解液。
电芯的制备：将上述正负极极片和隔离膜通过卷绕方式制成电芯，正负极极片的留白集流体分别位于卷绕后电芯的两头，由于本发明并不涉及正负极的极性区分，因此以下说明中均不再对正负极进行区别描述。请参阅图1A、 图1B和图1C，本实施例的电芯中，正负极极片的留白集流体10上均焊接有对应极性的极耳12，电芯通过两极的极耳12与外界电路相连。由于留白集流体10上与极耳12不对齐的边缘区域为装配时的易打折区域14，因此，为了避免留白集流体10在装配过程中打折，同时为了给电解液留出更多的传输通道，将留白集流体10上每一个易打折区域14都沿弧线冲切掉一部分，使易打折区域14成为半封闭的内凹弧形通道，从而使电解液可以沿图中箭头所示方式传输至正负极极片。
电池的制备：对上述电芯进行封装，再经过注液、化成、抽气成型后，即可得到软包电池。
实施例2
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图2A和图2B，本实施例与实施例1的区别仅在于：本实施例除将易打折区域14冲切为内凹弧形通道外，还在极耳12的焊印16后方(指焊印16与电芯主体部3之间的区域，以下实施例同)的留白集流体10上冲切出1个全封闭的椭圆形孔状结构20；椭圆形孔状结构20的长轴与焊印16平行，其面积占冲切前留白集流体10面积的6％，以保证过流能力。
实施例3
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图3A和图3B，本实施例与实施例1的区别仅在于：本实施例并未将易打折区域14冲切为内凹弧形通道，而是冲切为半封闭的三角形通道。
实施例4
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图4A和图4B，本实施例与实施例1的区别仅在于：本实施例并未将易打折区域14冲切为内凹弧形通道，而是将易打折区域14完全冲切掉，形成直角通道。
实施例5
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图5A和图5B，本实施例与实施例1的区别仅在于：本实施例并未对易打折区域14进行冲切，而是在极耳12的焊印16后方的留白集流体10上冲切出1个全封闭的椭圆形孔状结构20；椭圆形孔状结构20的长轴与焊印16平行，其面积占冲切前留白集流体10面积的6％，以保证过流能力。
实施例6
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图6A和图6B，本实施例与实施例1的区别仅在于：本实施例并未对易打折区域14进行冲切，而是在极耳12的焊印16后方的留白集流体10上冲切出一排4个全封闭的圆形孔状结构22；圆形孔状结构22的面积之和占冲切前留白集流体10面积的2％，以保证过流能力。
实施例7
除留白集流体10的冲切方式外，本实施例与实施例1完全相同。
请参阅图7A和图7B，本实施例与实施例1的区别仅在于：本实施例并未对易打折区域14进行冲切，而是在极耳12的焊印16后方的留白集流体10上冲切出一个全封闭的矩形孔状结构24；矩形孔状结构24的长边与焊印16平行，其面积占冲切前留白集流体10面积的10％，以保证过流能力。
对比例1
请参阅图8A和图8B，本对比例与实施例1完全相同，只是在电芯制备时不对留白集流体10进行冲切，保留全部的易打折区域14。
实施例8
请参阅图9，本实施例与实施例1的区别在于：首先，本实施例的电池为硬壳电池，其正负极极片的留白集流体10上并未焊接极耳12，而是直接与跟电池顶盖30连接的正负极转接片32焊接，通过转接片32与外界电路相连；其次，留白集流体10的冲切方式是在转接片32的焊印18的后方冲切出一排4个全封闭的圆形孔状结构22；圆形孔状结构22的面积之和占留 白集流体10面积的3％，以保证过流能力。
本实施例所采用的正极极片、负极极片、隔离膜、电解液等与实施例1完全相同，此处不再赘述。
电池的制备：对上述电芯进行封装，再经过注液、化成、抽气成型后，即可得到硬壳电池。
对比例2
请参阅图10，本对比例与实施例8完全相同，只是在电芯制备时不对留白集流体10进行冲切，使焊印18后方的留白集流体10保持原状。
需要说明的是，本发明各实施例在导电片焊印后方的留白集流体上冲切出的孔状的全封闭通道，如椭圆形孔状结构20、圆形孔状结构22、矩形孔状结构24等，其特征尺寸均为1～10毫米。
各实施例和对比例制得的电芯和电池的性能测试
为了表征本发明对电芯电解液浸润性能和电池循环寿命的改善，对各实施例和对比例制得的电芯、电池进行以下测试，并将测试结果记录在表1。
1)将电芯浸泡在电解液中5小时，然后取出，放置在90℃下进行烘干；以电芯的内阻是否大于100MΩ作为判断是否烘干的依据，如大于则表示已经烘干；记录各电芯的烘干时间。
2)对电芯进行3C充电倍率测试，记录3C充电至80％SOC所需时间。
3)循环性能测试：使电池在60℃、2C/3C下循环800周，考察其容量保持率。在循环测试试验中，电压范围为2.8V～4.2V，以2C的倍率进行充电，以3C的倍率进行放电。循环容量保持率是第800次循环的3C放电容量相对于第2次放电容量的百分比。
表1、各实施例及对比例的电芯及电池测试结果
Figure PCTCN2017089536-appb-000001
Figure PCTCN2017089536-appb-000002
从表1的测试结果可以看出：本发明电芯对于电解液的吸收速度有了大幅提高；当电芯中的电解液传输通道拓宽后，电池的充电倍率也有了明显地改善，同时循环性能也得到了有益改善。
综上所述，本发明电芯在保证留白集流体具有足够过流能力的前提下，通过在易打折区域和/或导电片焊印后方的留白集流体上冲切出电解液通道，一方面有效防止易打折区域打折后阻碍电解液传输，另一方面打通了极耳/转接片焊印封闭的电解液传输通道，从而大幅提高了电解液对极片的浸润速度，显著减少了注液后电芯的静置浸润时间，同时，还能保证循环后期电芯内部的电解液保有量，有效改善了电芯的循环寿命。另外，本发明电芯的冲切工艺简单，因此能广泛快速地在不同电池中得以应用。
根据上述说明书的揭示和教导，本发明所属领域的技术人员还可以对上述实施方式进行适当的变更和修改。因此，本发明并不局限于上面揭示和描述的具体实施方式，对本发明的一些修改和变更也应当落入本发明的权利要求的保护范围内。此外，尽管本说明书中使用了一些特定的术语，但这些术语只是为了方便说明，并不对本发明构成任何限制。

Claims (20)

  1. 一种电芯，包括分别设有留白集流体的正负极极片，正负极极片的留白集流体分别焊接有用于与外界电路相连的导电片；其特征在于，所述正极极片和/或负极极片的留白集流体上冲切有电解液传输通道；电解液传输通道的冲切方式包括以下一种或两种，一是在留白集流体的与导电片不对齐的边缘区域冲切出半封闭通道，二是在留白集流体上冲切出孔状的全封闭通道。
  2. 根据权利要求1所述的电芯，其特征在于，所述半封闭通道为将留白集流体的与导电片不对齐的边缘区域全部或部分冲切掉而形成的直角通道、内凹弧形通道或三角形通道。
  3. 根据权利要求1所述的电芯，其特征在于，所述孔状的全封闭通道为圆形孔状结构、椭圆形孔状结构、矩形孔状结构、三角形孔状结构或梯形孔状结构。
  4. 根据权利要求1所述的电芯，其特征在于，所述孔状的全封闭通道的面积占冲切前留白集流体面积的2％～10％。
  5. 根据权利要求1所述的电芯，其特征在于，所述孔状的全封闭通道为并排的多个孔状结构。
  6. 根据权利要求1所述的电芯，其特征在于，所述孔状的全封闭通道为一个长方形孔状结构或是一个椭圆形孔状结构，长方形孔状结构的长边或椭圆形孔状结构的长轴与焊印平行。
  7. 根据权利要求1所述的电芯，其特征在于，所述导电片为正负极耳，或为与电池顶盖连接的正负极转接片。
  8. 根据权利要求1所述的电芯，其特征在于，所述电芯为卷绕型电芯，其留白集流体上的电解液传输通道是在电芯卷绕前冲切出来的，或是在电芯卷绕后冲切出来的。
  9. 一种电池，包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内；其特征在于，所述电芯为权利要求1-8中任一项所述的电芯。
  10. 一种电芯，包括各设有留白集流体的正极极片和负极极片，正极极片的留白集流体和负极极片的留白集流体各焊接有导电片，正极极片的留白集流体和负极极片的留白集流体各在与导电片焊接的部位形成焊印；
    其特征在于，
    正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向贯通留白集流体而形成的孔状的全封闭通道，且全封闭通道位于焊印的沿长度方向的内侧；和/或，
    正极极片的留白集流体和负极极片的留白集流体中的至少一个设置有通过沿厚度方向贯通留白集流体的拐角部而形成的半封闭通道，且半封闭通道位于焊印的沿宽度方向的一侧。
  11. 根据权利要求10所述的电芯，其特征在于，所述孔状的全封闭通道在垂直于厚度方向的平面内的投影为圆形、椭圆形、矩形、三角形或梯形。
  12. 根据权利要求10所述的电芯，其特征在于，所述孔状的全封闭通道在垂直于厚度方向的平面内的投影为并排的多个孔。
  13. 根据权利要求10所述的电芯，其特征在于，所述孔状的全封闭通道在垂直于厚度方向的平面内的投影为长方形且长方形的长边与焊印平行，或者所述孔状的全封闭通道在垂直于厚度方向的平面内的投影为椭圆形且椭圆形的长轴与焊印平行。
  14. 根据权利要求10所述的电芯，其特征在于，所述孔状的全封闭通道通过冲切的方式形成。
  15. 根据权利要求14所述的电芯，其特征在于，所述孔状的全封闭通道的面积占冲切前留白集流体面积的2％～10％。
  16. 根据权利要求10所述的电芯，其特征在于，
    所述电芯为卷绕型电芯，正极极片的留白集流体和负极极片的留白集流体沿长度方向分别朝相反的方向延伸。
  17. 根据权利要求10所述的电芯，其特征在于，所述正极极片的留白集流体和/或负极极片的留白集流体在垂直于厚度方向的平面内的投影为梯形。
  18. 根据权利要求10所述的电芯，其特征在于，所述半封闭道通在垂直于厚度方向的平面内的投影为内凹弧形。
  19. 根据权利要求10所述的电芯，其特征在于，两个导电片分别为正极耳和负极耳，或两个导电片分别为与电池顶盖连接的正极转接片和负极转接片。
  20. 一种电池，包括电池壳体、电芯和电解液，电芯和电解液均封装在电池壳体内；其特征在于，所述电芯为权利要求10-19中任一项所述的电芯。
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