CN111162306B - Lithium ion secondary battery, electrode lamination battery cell thereof and battery cell lamination method - Google Patents
Lithium ion secondary battery, electrode lamination battery cell thereof and battery cell lamination method Download PDFInfo
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- CN111162306B CN111162306B CN202010004197.1A CN202010004197A CN111162306B CN 111162306 B CN111162306 B CN 111162306B CN 202010004197 A CN202010004197 A CN 202010004197A CN 111162306 B CN111162306 B CN 111162306B
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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
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The embodiment of the invention discloses a lithium ion secondary battery, an electrode lamination battery cell thereof and a battery cell lamination method, wherein the method comprises the steps of obtaining a primary electrode group, placing a first positive pole piece on one side of a diaphragm, and placing a first negative pole piece on the other side of the diaphragm to form the primary electrode group; obtaining a central lamination group, and turning a primary electrode 180 degrees around a rotation axis so that the diaphragm covers the first positive pole piece and the first negative pole piece, and forming the central lamination group; and obtaining a peripheral lamination group, placing a second positive pole piece and a second negative pole piece at two sides of a diaphragm covering the central lamination group, and turning the central lamination group by 180 degrees around a rotation axis so that the diaphragm covers the second positive pole piece and the second negative pole piece to form the peripheral lamination group. The lithium ion battery adopts the integral folding and wrapping mode, so that the technical problems of short service life and low safety performance of the battery caused by the lithium precipitation phenomenon are avoided, and the service life and the input and output characteristics of the battery are improved.
Description
Technical Field
The embodiment of the invention relates to the technical field of battery production, in particular to a lithium ion secondary battery, an electrode lamination battery cell thereof and a battery cell lamination method.
Background
The battery is a structure in which chemical energy of an active material inside is converted into electric energy by a redox reaction, and the chemical reaction is replaced by an electrochemical reaction and is transmitted to the outside through a lead. With the miniaturization and weight reduction of devices and the realization of the generalization of applications of portable electronic products, lithium ion secondary batteries with high energy density have come into force. The lithium ion secondary battery is manufactured by using substances capable of lithium ion intercalation and deintercalation as a positive pole piece and a negative pole piece, and filling organic electrolyte or polymer electrolyte in the middle of the positive pole piece and the negative pole piece, wherein the lithium ions are subjected to oxidation and reduction reactions in the process of intercalation and deintercalation in the positive pole piece and the negative pole piece to form electric energy.
Referring to fig. 1, 2a and 2b, in the prior art, a lithium ion secondary battery may be formed by a lamination method as shown in fig. 1, or by a winding method as shown in fig. 2 a.
When the lamination mode is adopted, the positive pole piece, the diaphragm and the negative pole piece are overlapped in a Z-shaped mode of maintaining a certain position of lamination in sequence. As shown in fig. 1, a positive electrode sheet 12, a separator 11, and a negative electrode sheet 13 cut to a predetermined specification are sequentially stacked in a Z-shaped stacking manner to form an electrode stack 10 for a lithium ion secondary battery. However, from the specification, generally, the positive electrode plate is smaller than the negative electrode plate, a diaphragm is interposed between the positive electrode plate and the negative electrode plate, and if the positive electrode plate is larger than the negative electrode plate or the positive electrode plate is separated from the range of the size of the negative electrode plate, the laminated battery reacts on the surface of the corresponding negative electrode plate to cause Lithium (Lithium) precipitation, which on one hand weakens the service life of the Lithium ion secondary battery at a high speed, and on the other hand, because of the occurrence of the Lithium precipitation caused by the side reaction between the positive and negative electrode plates, internal short circuit is caused, which may cause safety hazards such as ignition and explosion, and the diaphragm is required to separate each positive electrode plate from each negative electrode plate, which may decrease the lamination process speed.
When the Z-shaped lamination mode is adopted, the tension of the diaphragm 11 covering the positive electrode plate 12 and the negative electrode plate 13 is weak in the lamination process, and the positive electrode plate or the negative electrode plate is easy to deviate in the subsequent treatment process after the lamination is completed, under the condition, the positive electrode plate 12 is separated from the range of the negative electrode plate 13, a separation part 18 is generated, and at the moment, the negative electrode plate 13 at the position where the positive electrode plate 12 is separated from the negative electrode plate 13 is reacted to form the Lithium (Lithium) precipitation, so that the technical problems of short service life and low safety performance of the battery caused by the Lithium precipitation phenomenon are solved. In addition, after the electrode is manufactured, blank parts 19 are easily generated between the diaphragm and the electrode, and the battery is expanded due to residues in the battery in the charging and discharging process.
When a winding mode is adopted, as shown in fig. 2a and 2b, stress difference exists between the edge part and the central part of the battery cell during winding, the corresponding linear distances of the positive pole piece and the negative pole piece are inconsistent, so that the mobility of lithium ions is inconsistent, deviation h is generated, excessive reaction occurs at a relatively close part, reaction at a relatively far part is not in place, so that a lithium precipitation phenomenon is generated, and the technical problems of short service life and low safety performance of the battery caused by the lithium precipitation phenomenon also exist.
Disclosure of Invention
Therefore, the embodiment of the invention provides a lithium battery, an electrode lamination battery cell thereof and a battery cell lamination method, which are used for at least partially solving the technical problems of short service life and low safety performance of the battery caused by a lithium precipitation phenomenon.
In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:
an electrode lamination cell for a lithium ion secondary battery, comprising a central lamination stack and at least one peripheral lamination stack;
the central lamination group comprises a diaphragm, a first positive pole piece arranged on one side of the diaphragm and a first negative pole piece arranged on the other side of the diaphragm, and the central lamination group is turned over by a preset angle around a rotation axis so as to enable the diaphragm to cover the first positive pole piece and the first negative pole piece;
the peripheral lamination group comprises a central lamination group, peripheral lamination groups positioned on one sides of the peripheral lamination groups close to the central lamination group, a second positive pole piece arranged on one side of the diaphragm, and a second negative pole piece arranged on the other side of the diaphragm, wherein the second positive pole piece and the first negative pole piece are separated by a layer of the diaphragm, and the second negative pole piece and the first positive pole piece are separated by a side of the diaphragm;
and the peripheral laminated stack is overturned by a preset angle around a rotation axis so that the diaphragm covers the second positive pole piece and the second negative pole piece.
Further, the rotation axis, the first positive pole piece, the first negative pole piece, the second positive pole piece and the second negative pole piece are all arranged in parallel, and the rotation axis is perpendicular to the length direction of the diaphragm.
Further, still include the diaphragm axle, the diaphragm axle sets up in at least one end of diaphragm.
Furthermore, the number of the diaphragm shafts is two, and the two diaphragm shafts are respectively arranged at two ends of the diaphragm and stretch the diaphragm.
Furthermore, the first positive pole piece and the first negative pole piece are both single-sided electrodes, and the non-electrode surfaces of the two single-sided electrodes are arranged oppositely.
Further, the rotation axis passes through a center line of a length direction of the diaphragm, and/or the preset angle is 180 °.
The invention also provides a lithium ion secondary battery, which comprises the electrode lamination battery core.
The invention also provides a cell lamination method for processing the electrode lamination cell, which comprises the following steps:
obtaining a primary electrode group, placing a first positive electrode piece on one side of a diaphragm, and placing a first negative electrode piece on the other side of the diaphragm to form the primary electrode group;
obtaining a central lamination set, turning a primary electrode 180 ° around a rotation axis, so that the diaphragm covers the first positive electrode sheet and the first negative electrode sheet, and forming the central lamination set, wherein the rotation axis passes through a center line of a length direction of the diaphragm;
obtaining a peripheral lamination group, placing a second positive pole piece on the outer surface of one side of a diaphragm covering the central lamination group, placing a second negative pole piece on the outer surface of the other side of the diaphragm covering the central lamination group, and turning the central lamination group by 180 degrees around a rotation axis so that the diaphragm covers the second positive pole piece and the second negative pole piece to form the peripheral lamination group;
and repeating the step of obtaining the peripheral laminated sheet group, placing the positive pole piece and the negative pole piece in sequence, and covering the diaphragm outside the newly added positive pole piece and negative pole piece through overturning until the preset number of electrodes are placed to form the electrode laminated cell.
Further, the positive pole pieces adopted by the method are all prepared by adopting active substances, the preparation method of the positive pole pieces comprises the steps of mixing lithium nickel cobalt manganese acid ester, carbon black serving as a conductive agent and PVDF serving as an adhesive into NMP to form slurry, and coating the formed slurry on an aluminum current collector for drying to obtain the positive pole pieces; and/or the presence of a gas in the atmosphere,
the negative pole piece is prepared by mixing graphite, carbon black serving as a conductive agent and PVDF serving as a binder into NMP to form slurry, and coating the slurry on a copper current collector for drying to obtain the negative pole piece.
Further, before acquiring the primary electrode set, the method further comprises:
a diaphragm shaft is provided at least one end of the diaphragm to stretch the diaphragm through the diaphragm shaft.
According to the Lithium ion secondary battery and the electrode lamination battery core and the battery core lamination method thereof provided by the invention, the overall and uniform increase of the stress on each positive electrode plate, each diaphragm and each negative electrode plate is realized through the integral folding and wrapping mode, the surface characteristics are improved through the diaphragms capable of maintaining uniform tension, and the diaphragms completely wrap the edge parts on the left side and the right side of the battery core, so that the problem of arrangement deviation of the positive electrode plates and the negative electrode plates in the battery core is solved, the Lithium separation (Lithium bromide) phenomenon caused by the deviation of the electrode plates is further avoided, the technical problems of short service life and low safety performance of the battery caused by the Lithium separation phenomenon are further avoided, and the service life and the input and output characteristics of the battery are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
The structures, the proportions, the sizes, and the like shown in the specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical essence, and any modifications of the structures, changes of the proportion relation, or adjustments of the sizes, should still fall within the scope of the technical contents disclosed in the present invention without affecting the efficacy and the achievable purpose of the present invention.
Fig. 1 is a schematic structural diagram of an electrode laminated cell manufactured by a Z-shaped lamination method in the prior art;
fig. 2a is a schematic structural diagram of an electrode lamination cell using a winding manner in the prior art;
fig. 2b is a schematic diagram of a defect in an electrode lamination cell obtained by a prior art processing method;
fig. 3 is a schematic cross-sectional structure view of an electrode lamination cell provided in the present invention;
fig. 4a to fig. 4e are schematic process flow diagrams of a cell lamination method provided in the present invention;
FIG. 5 is an enlarged view of a portion of FIG. 3;
FIG. 6a is a graph showing evaluation of life characteristics of batteries of examples and comparative examples;
fig. 6b is an evaluation graph of the output characteristics of the batteries of the examples and comparative examples.
Detailed Description
The present invention is described in terms of specific embodiments, and other advantages and benefits of the present invention will become apparent to those skilled in the art from the following disclosure. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In one embodiment, the present invention provides an electrode laminated cell for a lithium ion secondary battery, the electrode laminated cell includes a central laminated sheet set and at least one peripheral laminated sheet set, it should be understood that the cell is a structure formed by a plurality of positive pole pieces and a plurality of negative pole pieces separated and wrapped by a diaphragm, and the division into the laminated sheet sets is only for descriptive convenience and does not represent structural limitations or subordinates.
As shown in fig. 3, the central lamination group 130 includes a separator 110, a first positive pole piece 121 disposed on one side of the separator 110, and a first negative pole piece 122 disposed on the other side of the separator, and is turned around a rotation axis by a predetermined angle so that the separator covers the first positive pole piece 121 and the first negative pole piece 122; in this embodiment, the first positive electrode tab 121 is disposed on the upper side of the separator 110, and the first negative electrode tab 122 is disposed on the lower side of the separator 110, but in other embodiments, the first positive electrode tab 121 may be disposed on the lower side of the separator 110, and the first negative electrode tab 122 may be disposed on the upper side of the separator 110, that is, as long as the polarities of the electrodes on both sides of the separator 110 are opposite.
The peripheral lamination group comprises a central lamination group 130, peripheral lamination groups positioned on one side of the peripheral lamination group close to the central lamination group, a second positive pole piece 124 arranged on one side of the diaphragm, and a second negative pole piece 123 arranged on the other side of the diaphragm, wherein the second positive pole piece 124 is separated from the first negative pole piece 122 by a layer of the diaphragm 110, and the second negative pole piece 123 is separated from the first positive pole piece 121 by a side of the diaphragm 110; also, in this embodiment, the second positive electrode tab 124 is disposed on the lower side of the separator 110, and the second negative electrode tab 123 is disposed on the upper side of the separator 110, but in other embodiments, the second positive electrode tab may be disposed on the upper side of the separator, and the second negative electrode tab may be disposed on the lower side of the separator, that is, as long as the polarities of the electrodes on both sides of the separator are opposite.
The peripheral lamination stack is turned around the rotation axis a, which passes through the center line of the length direction of the separator, by a preset angle, i.e. 180 °, as shown in fig. 4a-4e, so that the separator covers the second positive pole piece 124 and the second negative pole piece 123, the lamination stack is rotated in the direction of the illustrated circular arrow, where the dotted line is the rotation axis a.
In order to improve the battery performance, the rotation axis a, the first positive pole piece 121, the first negative pole piece 122, the second positive pole piece 124 and the second negative pole piece 123 are all arranged in parallel, and the rotation axis a is perpendicular to the length direction of the diaphragm 110.
In the use process, in order to ensure that the diaphragm 110 has sufficient tensile force, thereby avoiding the occurrence of the phenomenon of lithium precipitation, the battery cell further comprises a diaphragm shaft, and the diaphragm shaft is arranged at least one end of the diaphragm. Preferably, the diaphragm shafts are two, that is, a first diaphragm shaft 171 provided at one end and a second diaphragm shaft 172 provided at the other end, which are separately provided at both ends of the diaphragm and simultaneously stretch the diaphragm toward both ends, so as to provide a sufficient stretching force to the diaphragm.
Optionally, the first positive electrode tab 121 and the first negative electrode tab 122 are both single-sided electrodes, and non-electrode surfaces of the two single-sided electrodes are disposed oppositely. Wherein, the non-electrode surface of the single-side electrode is the single side of the current collector without slurry coating. Under the structure, the arrangement form of the single-sided electrodes on the two sides of the diaphragm can be positive electrode to positive electrode, negative electrode to negative electrode, or positive electrode to negative electrode; when the single-sided electrode is a positive electrode to a positive electrode or a negative electrode to a negative electrode, lamination can be started in a mode that no electrode is placed in the innermost diaphragm layer. As shown in fig. 3, although the positive electrode and the negative electrode are laminated in an intersecting manner with the diaphragm 110 as the center in the battery cell, the polarities of the electrodes located on the same side of the diaphragm 110 are the same, and the polarities of the electrodes located on different sides of the diaphragm are opposite, and the battery cell is assembled by rotating the diaphragm under the condition that the designated force increases the tension to both sides, so that the internal electrode pole pieces of the battery cell cannot move after being molded, and the problems of dislocation of the positive electrode pole pieces and the negative electrode pole pieces or blank between the electrode pole pieces and the diaphragm are avoided. Meanwhile, the way of maintaining the tension of the separator 110 in the longitudinal direction in the present invention is not particularly limited, and for example, a separator shaft may be disposed at each end of the separator 110 in the longitudinal direction to increase the tension, or a separator shaft may be disposed at only one side to increase the tension at one side and maintain the uniform tension of the whole separator by the force generated during winding at the other side.
In the above specific embodiment, the electrode laminated battery cell realizes comprehensive and uniform increase of stress on each positive electrode plate, each diaphragm and each negative electrode plate through the form of integrally turning over the folded package, and improves the surface characteristics through the diaphragm capable of maintaining uniform tension, so that the diaphragm completely covers the edge parts on the left side and the right side of the battery cell, the problem of arrangement offset of the positive electrode plates and the negative electrode plates in the battery cell is solved, the phenomenon of Lithium deposition (Lithium nitride) caused by electrode plate offset is avoided, the technical problems of short service life and low safety performance of the battery caused by the Lithium deposition phenomenon are avoided, and the service life and the input and output characteristics of the battery are improved.
In addition to the electrode laminated cell, the present invention also provides a lithium ion secondary battery including the electrode laminated cell, and other structures of the lithium ion secondary battery refer to the prior art, which is not described herein again.
Further, the present invention also provides a cell lamination method for processing the electrode lamination cell, as shown in fig. 4a to 4e, in a specific embodiment, the method includes:
obtaining a primary electrode group, placing a first positive pole piece on one side of a diaphragm, and placing a first negative pole piece on the other side of the diaphragm to form the primary electrode group;
obtaining a central lamination group, and turning a primary electrode 180 degrees around a rotation axis so that the diaphragm covers the first positive pole piece and the first negative pole piece, and forming the central lamination group, wherein the rotation axis passes through a center line of the diaphragm in the length direction;
obtaining a peripheral lamination group, placing a second positive pole piece on the outer surface of one side of a diaphragm covering the central lamination group, placing a second negative pole piece on the outer surface of the other side of the diaphragm covering the central lamination group, and turning the central lamination group by 180 degrees around a rotation axis so that the diaphragm covers the second positive pole piece and the second negative pole piece to form the peripheral lamination group;
and repeating the step of obtaining the peripheral laminated stack, placing the positive pole piece and the negative pole piece in sequence, and covering the diaphragm outside the newly added positive pole piece and the newly added negative pole piece through overturning until the preset number of electrodes are placed, so as to form the electrode laminated battery cell.
In the actual processing process, a first positive pole piece is placed on one surface of the diaphragm with uniform stress maintained on the two surfaces, and a first negative pole piece is placed in the opposite direction, so that the initial stage of the electrode group is formed, namely a primary electrode group is obtained; rotating the primary electrode group for 180 degrees by taking an axis which passes through the central part of the diaphragm and is vertical to the horizontal direction of the diaphragm as a rotating axis to form a first-stage laminated group, namely obtaining a central laminated group; a second cathode pole piece is placed on the diaphragm on the outer side of the first cathode pole piece, a second anode pole piece is placed on the diaphragm on the outer side of the first cathode pole piece, and the second cathode pole piece rotates 180 degrees in the same direction with the same rotation axis to form a lamination group at the second stage, namely a peripheral lamination group is obtained; and the same mode is used for repeatedly laminating the electrode pole pieces according to the specified quantity, then the residual diaphragms on the two sides are placed on the same side, and finally the manufacturing stage of the battery cell laminated stack is completed.
The preparation method of the positive pole piece comprises the steps of mixing lithium nickel cobalt manganese acid ester, carbon black serving as a conductive agent and PVDF serving as an adhesive into NMP to form slurry, coating the formed slurry on an aluminum current collector, and drying to obtain the positive pole piece; the negative pole piece adopted by the method is prepared from active substances, and the preparation method of the negative pole piece comprises the steps of mixing graphite, carbon black serving as a conductive agent and PVDF serving as a binder into NMP to form slurry, coating the slurry on a copper current collector and drying to obtain the negative pole piece.
Further, in order to increase the diaphragm tension, before acquiring the primary electrode group, the method further comprises: a diaphragm shaft is provided at least one end of the diaphragm to stretch the diaphragm through the diaphragm shaft, and preferably both ends, i.e., the first diaphragm shaft 171 and the second diaphragm shaft 172, may be provided to provide a more uniform tension by stretching to both sides.
The present invention will be described in detail below by comparing examples with comparative examples, and the following examples are only for describing the present invention in more detail, so the scope of the present invention is not limited to the following examples.
Example 1
The first positive electrode piece is an active substance, lithium nickel cobalt manganese acid ester (LiNixCoyMnzO 2) and carbon black are used as conductive agents, PVDF (polyvinylidene fluoride) serving as a binder is mixed into NMP (N-methyl pyrollidone) to form slurry, and the formed slurry is coated on an aluminum current collector and dried to form the positive electrode. The first negative electrode plate is formed by forming slurry by the same combination except that graphite is used for replacing lithium transfer metal oxide in the positive electrode battery, and then coating the formed slurry on a copper current collector and drying to form the negative electrode.
And the positive pole piece and the negative pole piece are cut according to the specified size, and the specification of the negative pole piece is larger than that of the positive pole piece. The separator 110 is a porous film made of polyethylene, and the size of the separator 110 must be larger than that of the negative electrode to prevent the negative electrode from contacting the positive electrode.
In order to ensure that the lamination of the electrodes takes place at the very centre of a length of membrane, one side of the membrane shaft is stretched with a certain spring force to maintain the elasticity of the membrane.
As shown in fig. 4b to 4e, the primary electrode group 130 consisting of the positive electrode, the separator, and the negative electrode is rotated by 180 ° in a linear direction with the separator kept under uniform tension. Thereafter, the electrode is again placed on the diaphragm and rotated 180 ° to complete the first-stage lamination stack 140, the lamination and winding are repeated again to complete the second-stage lamination stack 150 and this operation is repeated 30 times, and the diaphragm 110 is placed on one side to complete the lamination stack 160 of the present invention.
And inserting the lithium ion secondary battery into the aluminum plastic film after the assembly is completed according to the manufacturing method, only one surface is reserved, and the other surfaces are packaged to complete the manufacturing of the lithium ion secondary battery. Then, a nonaqueous electrolyte solution of a carbonate (carbonate) series containing a lithium salt is injected and vacuum-packed, and after the electrolyte is sufficiently impregnated into the electrode, a charge and discharge process is performed to complete the production of the lithium ion secondary battery.
Example 2
A lithium ion secondary battery was produced using the same positive electrode and negative electrode as in example 1, stretched on both sides of the separator shaft, and connected to the other both sides of the separator to be stacked and wound, using the same conditions as in example 1.
Example 3
A laminate stack was fabricated in the same manner as in example 1 above, but a lithium ion secondary battery was fabricated using a single-sided coated and dried single-sided positive electrode 125 as shown in fig. 5 in the preliminary laminate-forming stage, all of which were under the same conditions as those used in example 1.
As shown in fig. 5, the innermost side of the stack of electrode laminations is laminated in a line-of-sight manner using a single-sided paste-coated, single-sided negative electrode 126, and the non-paste-coated opposite side.
Comparative example 1
A lithium ion secondary battery was assembled by stacking the same electrodes as in example 1 in a conventional "Z" stacking manner as shown in fig. 1.
Comparative example 2
A lithium ion secondary battery was assembled by stacking electrodes in the same manner as in example 1 in a conventional winding and stacking manner as shown in fig. 2a and 2 b.
Based on the above examples 1 to 3 and comparative examples 1 to 2, the batteries fabricated in the above examples and comparative examples were charged to 4.2V at 1.0C and constant voltage and constant current using a charge and discharge tester, as shown in fig. 6a and 6b. After the discharge at constant current and 1.0C to 3.0V, the battery life characteristics were evaluated at room temperature, and the test results are shown in fig. 6a. In fig. 6a, in examples 1 to 3, the stack was rotated while increasing the tension of the separator during the manufacturing process, so that the arrangement of the electrodes was good and there was no blank between the separator and the electrodes, and the residual discharge capacity remained at 95.5% or more after 800 cycles of charge and discharge. However, in the conventional "Z" type (comparative example 1), the positive electrode and the negative electrode were misaligned, which resulted in an increase in the thickness of the battery due to side reactions after the charge and discharge processes, and the residual capacity was only 93% after 800 cycles of charge and discharge due to the depletion of the electrolyte. The conventional winding method (comparative example 2) maintained a good charge/discharge life up to 500 cycles of the charge/discharge cycle test, but the residual capacity after 510 cycles of the charge/discharge was extremely reduced due to the occurrence of internal stress and dislocation, and the residual discharge capacity after 800 cycles of the charge/discharge was only 91%.
The sample was charged to 4.2V at 1.0C and constant voltage and constant current using a charge-discharge tester. After the discharge at constant current and 5.0C to 3.0V, the battery power characteristics were evaluated at room temperature, and the test results are shown in fig. 6b. In fig. 6b, when the rated capacity of examples 1 to 3 was 1C, discharge was performed at a current 5 times the rated capacity, the voltage at the initial stage of discharge was 4.1V, the internal resistance was small, and the discharge voltage curve also tended to be higher than that of examples 1 and 2, and thus the discharge capacity was also high. In cases 1 and 2, the initial discharge voltage was 4.1V or less, and it was found that the initial voltage was significantly lowered compared to the cases 1 to 3, and thus the internal resistance was high. And the discharge capacity also appears to be reduced compared to the example cases 1 to 3.
Therefore, in the above specific embodiment, the cell stacking method provided by the present invention realizes overall and uniform increase of stress on each positive electrode plate, each diaphragm and each negative electrode plate through the integral folding and wrapping manner, and improves the surface characteristics through the diaphragm capable of maintaining uniform tension, so that the diaphragm completely wraps the edge portions on the left and right sides of the cell, thereby solving the problem of arrangement offset of the positive electrode plate and the negative electrode plate in the cell, further avoiding the Lithium separation (Lithium bromide) phenomenon caused by the offset of the electrode plates, further avoiding the technical problems of short service life and low safety performance of the battery caused by the Lithium separation phenomenon, and improving the service life and the input and output characteristics of the battery.
The above embodiments are only for illustrating the embodiments of the present invention and are not to be construed as limiting the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made on the basis of the embodiments of the present invention shall be included in the scope of the present invention.
Claims (9)
1. An electrode lamination cell for a lithium ion secondary battery, comprising a central lamination stack and at least one peripheral lamination stack;
the central lamination group comprises a diaphragm, a first positive pole piece arranged on one side of the diaphragm and a first negative pole piece arranged on the other side of the diaphragm, and the central lamination group is turned over by a preset angle around a rotation axis so as to enable the diaphragm to cover the first positive pole piece and the first negative pole piece;
the peripheral lamination group comprises a central lamination group, peripheral lamination groups positioned on one sides of the peripheral lamination groups close to the central lamination group, a second positive pole piece arranged on one side of the diaphragm, and a second negative pole piece arranged on the other side of the diaphragm, wherein the second positive pole piece and the first negative pole piece are separated by a layer of the diaphragm, and the second negative pole piece and the first positive pole piece are separated by a side of the diaphragm;
the peripheral lamination group is turned over by a preset angle around a rotation axis so that the diaphragm covers the second positive pole piece and the second negative pole piece;
the first positive pole piece and the first negative pole piece are single-sided electrodes, and the non-electrode surfaces of the two single-sided electrodes are arranged oppositely;
the non-electrode surface of the single-sided electrode is a single surface of a current collector which is not coated with slurry, and the single-sided electrodes on two sides of the diaphragm are arranged in a positive electrode-positive electrode mode, a negative electrode-negative electrode mode or a positive electrode-negative electrode mode; when the single-sided electrode is a positive electrode to a positive electrode or a negative electrode to a negative electrode, lamination can be started by adopting a mode that no electrode is arranged in the innermost diaphragm layer, the positive electrode and the negative electrode in the battery cell are laminated in a mutually intersecting mode by taking the diaphragm as the center, the polarities of the electrodes positioned on the same side of the diaphragm are the same, the polarities of the electrodes positioned on different sides of the diaphragm are opposite, and the battery cell is assembled by rotating the diaphragm under the condition that the tension is increased to the two sides by appointed force.
2. The electrode lamination cell of claim 1, wherein the rotational axis, the first positive pole piece, the first negative pole piece, the second positive pole piece, and the second negative pole piece are all arranged in parallel, and the rotational axis is perpendicular to the length direction of the separator.
3. The electrode lamination cell of claim 1, further comprising a separator shaft disposed at least one end of the separator.
4. The electrode lamination cell of claim 3, wherein there are two separator shafts, and the two separator shafts are respectively disposed at two ends of the separator and stretch the separator.
5. The electrode lamination cell according to any of claims 1 to 4, wherein the axis of rotation passes through a center line of the length of the separator and/or the predetermined angle is 180 °.
6. A lithium ion secondary battery comprising the electrode lamination cell of any one of claims 1 to 5.
7. A cell lamination process for processing an electrode lamination cell according to any of claims 1 to 5, the process comprising:
obtaining a primary electrode group, placing a first positive pole piece on one side of a diaphragm, and placing a first negative pole piece on the other side of the diaphragm to form the primary electrode group;
obtaining a central lamination group, and turning a primary electrode 180 degrees around a rotation axis so that the diaphragm covers the first positive pole piece and the first negative pole piece, and forming the central lamination group, wherein the rotation axis passes through a center line of the diaphragm in the length direction;
obtaining a peripheral laminated stack, placing a second positive electrode plate on the outer surface of one side of a diaphragm covering the central laminated stack, placing a second negative electrode plate on the outer surface of the other side of the diaphragm covering the central laminated stack, and turning the central laminated stack by 180 degrees around a rotation axis so that the diaphragm covers the second positive electrode plate and the second negative electrode plate, and forming the peripheral laminated stack;
and repeating the step of obtaining the peripheral laminated sheet group, placing the positive pole piece and the negative pole piece in sequence, and covering the diaphragm outside the newly added positive pole piece and negative pole piece through overturning until the preset number of electrodes are placed to form the electrode laminated cell.
8. The cell stacking method according to claim 7, wherein the positive electrode plates adopted in the method are all prepared from active substances, and the preparation method of the positive electrode plates comprises the steps of mixing lithium nickel cobalt manganese acid ester, carbon black serving as a conductive agent and PVDF serving as a binder into NMP to form slurry, coating the formed slurry on an aluminum current collector, and drying to obtain the positive electrode plates; and/or the presence of a gas in the atmosphere,
the negative pole piece adopted by the method is prepared from active substances, and the preparation method of the negative pole piece comprises the steps of mixing graphite, carbon black serving as a conductive agent and PVDF serving as a binder into NMP to form slurry, coating the slurry on a copper current collector and drying to obtain the negative pole piece.
9. The cell lamination method according to claim 7, wherein prior to obtaining the set of primary electrodes, the method further comprises:
a diaphragm shaft is provided at least one end of the diaphragm to stretch the diaphragm through the diaphragm shaft.
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| JP2004356047A (en) * | 2003-05-30 | 2004-12-16 | Canon Inc | Lithium secondary battery |
| JP2006079960A (en) * | 2004-09-10 | 2006-03-23 | Toshiba Battery Co Ltd | Flat nonaqueous electrolyte secondary battery |
| CN110289451A (en) * | 2019-07-03 | 2019-09-27 | 惠州市金芯科技有限公司 | A kind of button lithium battery and preparation method thereof |
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| JP3428452B2 (en) * | 1998-08-27 | 2003-07-22 | 三菱電機株式会社 | Battery with spiral electrode body and method of manufacturing the same |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004356047A (en) * | 2003-05-30 | 2004-12-16 | Canon Inc | Lithium secondary battery |
| JP2006079960A (en) * | 2004-09-10 | 2006-03-23 | Toshiba Battery Co Ltd | Flat nonaqueous electrolyte secondary battery |
| CN110289451A (en) * | 2019-07-03 | 2019-09-27 | 惠州市金芯科技有限公司 | A kind of button lithium battery and preparation method thereof |
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