METHOD FOR INSPECTING WELD STATES OF BATTERY

A method is provided to inspect weld states of a cylindrical battery. The cylindrical battery may include: a cylindrical jelly roll in which a first current collector, a first separator, a second current collector, and a second separator are sequentially stacked and wound, so as to extend in the vertical direction; a first collector plate which is coupled to the upper end of the jelly roll and to the lower surface of which the first current collector is firstly welded; and a second collector plate which is coupled to the lower end of the jelly roll and to the upper surface of which the second current collector is secondly welded. The method may include a first measurement step, a second measurement step, a first weld determination step, and a second weld determination step.

TECHNICAL FIELD

This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0089920 filed on Jul. 8, 2021, the entire disclosure of which is incorporated herein by reference for all purposes.

The present disclosure relates to a method for inspecting a welding state of a battery, and more specifically, to a method for inspecting a welding state of a battery which is capable of quickly and non-destructively inspecting a state of electrodes of a cylindrical battery.

BACKGROUND ART

In general, a current collector to which an active material is applied and an electrode tab for electrical connection to external electrical devices are connected together both physically and electrically in a battery by welding the current collector and the electrode tab. In the case of a poor welding state, the battery's operating efficiency is reduced, and depending on the situation, the poor welding state may result in damages to the battery. Therefore, it is crucial to accurately determine the welding state.

For a cylindrical battery, welds exist between the current collector and the electrode tab as well as between the electrode tab and a can. In order to inspect the welding states of these welds, a destructive inspection method for manually sampling welding regions has been performed.

Therefore, there existed a problem with the conventional method such as lots on hold when an issue with a welding state arises.

In order to solve this problem, there is a need for a new inspection method which is capable of in-line total inspection.

DISCLOSURE OF INVENTION

Technical Goals

The present disclosure relates to a method for inspecting a welding state of a battery, and an object is to provide a method for inspecting a welding state of a battery which is capable of quickly and non-destructively inspecting a state of electrodes of a cylindrical battery.

Technical objects to be achieved by the present disclosure are not limited to the technical problems as mentioned above, and other technical objects not mentioned will be clearly understood from the description below by those of ordinary skill in the art to which the present disclosure pertains.

Technical Solutions

A method for inspecting a welding state of a battery of an example embodiment includes: a first measuring step of measuring resistance by contacting a first probe unit with an upper surface of a first current collector plate; a second measuring step of measuring resistance by contacting a second probe unit with a lower surface of a second current collector plate; a first welding determining step of determining a state of the first welding based on the resistance value measured in the first measuring step; and a second welding determining step of determining a state of the second welding based on the resistance value measured in the second measuring step.

Advantageous Effects

According to a method for inspecting a welding state of a battery of example embodiments of the present disclosure, it is possible to perform in-line total inspection, thereby improving the quality of battery production and removing defective batteries in advance.

According to a method for inspecting a welding state of a battery of example embodiments of the present disclosure, it is possible to identify welding qualities within a short time period.

EXAMPLE EMBODIMENTS AND ASPECTS

A method for inspecting a welding state of a battery of an example embodiment may include: a first measuring step of measuring resistance by contacting a first probe unit with an upper surface of a first current collector plate; a second measuring step of measuring resistance by contacting a second probe unit with a lower surface of a second current collector plate; a first welding determining step of determining a state of the first welding based on a resistance value measured in the first measuring step; and a second welding determining step of determining a state of the second welding based on a resistance value measured in the second measuring step.

In the method for inspecting a welding state of a battery of an example embodiment, the first probe unit may include a plurality of first probes provided in a plurality of pairs, and the second probe unit may include a plurality of second probes provided in a plurality of pairs, wherein in the first measuring step, the plurality of first probes may contact different respective points of the first current collector plate to measure resistance values, and in the second measuring step, the plurality of second probes may contact different respective points of the second current collector plate to measure resistance values.

In the method for inspecting a welding state of a battery of an example embodiment, the first current collector plate may be provided in a cross shape in which a first linear region and a second linear region intersect with each other, and the second current collector plate may be provided in a cross shape in which a third linear region and a fourth linear region intersect with each other, wherein a region in which the first linear region and the second linear region overlap may be defined as a first intersection region, and a region in which the third linear region and the fourth linear region overlap may be defined as a second intersection region, wherein in the first measuring step, at least a pair of first probes among the plurality of first probes may measure a first resistance value by contacting the first linear region with the first intersection region interposed therebetween, and at least another pair of first probes among the plurality of first probes may measure a second resistance value by contacting a second linear region with the first intersection region interposed therebetween, and wherein in the second measuring step, at least a pair of second probes among the plurality of second probes may measure a third resistance value by contacting the third linear region with the second intersection region interposed therebetween, and at least another pair of second probes among the plurality of second probes may measure a fourth resistance value by contacting a fourth linear region with the second intersection region interposed therebetween.

In the first welding determining step of the method for inspecting a welding state of a battery of an example embodiment, a state of the first welding may be determined based on the first resistance value and the second resistance value, and in the second welding determining step, a state of the second welding may be determined based on the third resistance value and the fourth resistance value.

In the method for inspecting a welding state of a battery of an example embodiment, an arc-shaped adhesive portion may be provided on an edge of the first current collector, and the cylindrical battery may further include a can housing configured to house the jelly roll inside, wherein the adhesive portion is third welded to an inner perimeter surface of the can housing; and an electrode terminal fixed to a lower end of the can housing with an insulator interposed therebetween and fourth welded to the second current collector plate.

The method for inspecting a welding state of a battery of an example embodiment may further include: after the second welding determining step, a third measuring step of measuring a resistance value by contacting a probe with the first current collector plate and contacting another probe with an outer perimeter surface of the can housing; a fourth measuring step of measuring a resistance value by contacting a probe with the second current collector plate and contacting another probe with the electrode terminal; a third welding determination step of determining a state of the third welding based on the resistance value measured in the third measuring step; and a fourth welding determination step of determining a state of the fourth welding based on the resistance value measured in the fourth measuring step.

The resistance measurement in the first measuring step, the second measuring step, the third measuring step, and the fourth measuring step in the method for inspecting a welding state of a battery of an example embodiment may be carried out by a 4-wire low-resistance direct current method.

A method for manufacturing a battery of an example embodiment may include: a jelly roll forming step of forming a jelly roll by winding a sequential stack of the first current collector, the first separator, the second current collector, and the second separator; a first welding step of first welding the first current collector and the first current collector plate at an upper end of the jelly roll; a second welding step of second welding the second current collector and the second current collector plate at a lower end of the jelly roll; a first welding determining step of measuring resistance by contacting a first probe unit with an upper surface of the first current collector plate, and determining a state of the first welding based on the measured resistance value; a second welding determining step of measuring resistance by contacting a second probe unit with a lower surface of the second current collector plate, and determining a state of the second welding based on the measured resistance value; a third welding step of third welding the first current collector plate and the can housing; a fourth welding step of fourth welding the second current collector plate and the electrode terminal; a third welding determining step of measuring resistance by contacting a probe with the first current collector plate and contacting another probe with an outer perimeter surface of the can housing, and determining the third welding state based on the measured resistance value; a fourth welding determining step of measuring resistance by contacting a probe with the second current collector plate and contacting another probe with the electrode terminal, and determining the fourth welding state based on the measured resistance value; and a sealing step of injecting an electrolyte into the can housing and sealing the can housing.

DETAILED DESCRIPTION

Hereinafter, an example embodiment according to the present disclosure will be described in detail with reference to the accompanying drawings. Here, the size or shape of components shown in the drawings may be exaggerated for clarity and convenience of explanation In addition, terms specifically defined in consideration of the configuration and operation of the present disclosure may vary depending on the intention or custom of a user or operator. Definitions of these terms should be made based on the context throughout this specification.

In the description of the present disclosure, it should be noted that orientation or positional relationships indicated by the terms such as “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inside”, “outside”, “one side”, and “the other side” are based on orientation or positional relationships shown in the drawings or orientation or positional relationships usually of disposition when a product according to the present disclosure is used, are merely for the description and brief illustration of the present disclosure, and should not be construed as limiting the present disclosure because they are not suggesting or implying that the indicated apparatus or element must be configured or operated in the specified orientation with the specified orientation.

FIG.1is a perspective view illustrating a jelly roll100.FIG.2is a cross-sectional view illustrating coupling between a first current collector plate210, a second current collector plate220, and the jelly roll.FIG.3is a block diagram illustrating a method for inspecting a welding state of a battery of the present disclosure.FIG.4is a conceptual diagram illustrating a first measuring step S100and a second measuring step S200.FIG.5is a conceptual diagram illustrating principles of a first welding determining step S300and a second welding determining step S400.FIG.6is a plan view illustrating a first current collector plate210.FIG.7is a plan view illustrating a second current collector plate220.FIG.8is a cross-sectional view illustrating a cylindrical battery.FIG.9is a block diagram illustrating another example embodiment of the method for inspecting a welding state of a battery of the present disclosure.FIG.10is a conceptual diagram illustrating a third measuring step S500.FIG.11is a conceptual diagram illustrating a fourth measuring step S600.

Hereinafter, the method for inspecting a welding state of a battery of the present disclosure will be described in detail with reference toFIGS.1to11.

The method for inspecting a welding state of a battery of the present disclosure may be used for inspecting states of welding between parts for electrical connection in a cylindrical battery.

As shown inFIGS.1and2, a cylindrical battery subject to inspection according the method for inspecting a welding state of a battery of the present disclosure may include a jelly roll100having a cylindrical shape and extending in a vertical direction with a first current collector110, a first separator130, a second current collector120, and a second separator140being stacked sequentially and wound; a first current collector plate210coupled to an upper end of the jelly roll100, wherein the first current collector110is first welded to a lower surface of the first current collector plate210; and a second current collector plate220coupled to a lower end of the jelly roll100, wherein the second current collector120is second welded to an upper surface of the second current collector plate220.

In other words, as shown inFIG.1, the jelly roll100may be provided in a cylindrical shape with the vertical direction being a central axis, and an upper end of the first current collector110may protrude higher than upper ends of the second current collector120, the first separator130, and the second separator140, and a lower end of the second current collector120may protrude lower than lower ends of the first current collector110, the first separator130, and the second separator140.

The first current collector110may be an anode current collector or a cathode current collector coated with an anode active material or a cathode active material. When the first current collector110is an anode current collector, the second current collector120may be a cathode current collector, and when the first current collector110is a cathode current collector, the second current collector120may be an anode current collector.

As shown inFIG.2, the first current collector plate210and the second current collector plate220may be provided as plates in the shape of planes that are perpendicular to the vertical direction. The upper end of the first current collector110may be first welded to the lower surface of the first current collector210with a tilt angle, and the lower end of the second current collector120may be second welded to the upper surface of the second current collector220at a tilt angle.

The first welding and the second welding may be laser welding, ultrasonic welding, resistance welding, or the like.

As shown inFIG.3, the method for inspecting a welding state of a battery of the present disclosure may include:a first measuring step S100of measuring resistance by contacting a first probe unit400with an upper surface of the first current collector plate210;a second measuring step S200of measuring resistance by contacting a second probe unit500with a lower surface of the second current collector plate220;a first welding determining step S300of determining a state of the first welding with the resistance value measured in the first measuring step S100; anda second welding determining step S400of determining a state of the second welding with the resistance value measured in the second measuring step S200.

The first measuring step S100and the second measuring step S200may be performed before the jelly roll100is inserted into the can housing310after the current collectors and the current collector plates are welded during the manufacture of the battery.

As shown inFIG.4, in the first measuring step S100, the first probe unit400may be in contact with a side of the first current collector plate210that is opposite to the side where the first current collector110and the first current collector plate210contact each other, and in the second measuring step S200, the second probe unit500may be in contact with a side of the second current collector plate220that is opposite to the side where the second current collector120and the second current collector plate220contact each other, thereby allowing for measuring resistance values. As shown inFIG.5, even when resistance values are measured by contacting the probes with the opposite side of the welded side, a welding state of the side opposite to the measured side may be identified by analyzing the resistance values, because the welding state affects the resistance seen by the probes. In a cylindrical battery subject to the method for inspecting a welding state of a battery of the present disclosure, materials of the first current collector plate210and the second current collector plate220may be selected from aluminum, nickel, copper, and combinations thereof. The first current collector plate210and the second current collector plate220may be formed with a thickness ranging from 0.2 T to 0.4 T. Therefore, the welding state may be well reflected in the resistance values measured by contacting the probes to the side opposite to the welded side.

In the method for inspecting a welding state of a battery of the present disclosure, the first probe unit400may include a plurality of first probes410provided in a plurality of pairs, and the second probe unit500may include a plurality of second probes510provided in a plurality of pairs, wherein in the first measuring step S100, the plurality of first probes410contact different respective points of the first current collector plate210to measure resistance values, and in the second measuring step S200, the plurality of second probes510contact different respective points of the second current collector plate220to measure resistance values.

A pair of first probes410may be provided to include one anode probe and one cathode probe, and a pair of second probes510may also be provided to include one anode probe and one cathode probe.

Each of the plurality of pairs of first probes410may contact different respective points such that a first welding region214is interposed between the anode probe and the cathode probe, and each of the plurality of pairs of second probes510may contact different respective points such that a second welding region224is interposed between the anode probe and the cathode probe.

As shown inFIGS.6and7, in a cylindrical battery subject to the method for inspecting a welding state of a battery of the present disclosure, the first current collector plate210may be provided in a cross shape in which a first linear region211and a second linear region212intersect with each other, and the second current collector plate220may be provided in a cross shape in which a third linear region221and a fourth linear region222intersect with each other.

In this case, a region in which the first linear region211and the second linear region212overlap may be defined as a first intersection region213, and a region in which the third linear region221and the fourth linear region222overlap may be defined as a second intersection region223, wherein in the first measuring step S100, at least a pair of first probes410among the plurality of first probes410may measure a first resistance value by contacting the first linear region211with the first intersection region213interposed therebetween, and at least another pair of first probes410among the plurality of first probes410may measure a second resistance value by contacting the second linear region212with the first intersection region213interposed therebetween, and wherein in the second measuring step S200, at least a pair of second probes510among the plurality of second probes510may measure a third resistance value by contacting the third linear region221with the second intersection region223interposed therebetween, and at least another pair of second probes510among the plurality of second probes510may measure a fourth resistance value by contacting the fourth linear region222with the second intersection region223interposed therebetween.

Specifically, the pair of first probes410may contact the first linear region211with the first welding region214and the first intersection region213interposed therebetween, and more specifically, the pair of first probes410may contact both ends of the first linear region211. The another pair of first probes410may also contact the second linear region212with the first welding region214and the first intersection region213interposed therebetween, and more specifically, the another pair of first probes410may contact both ends of the second linear region212.

The pair of second probes510may contact the third linear region221with the second welding region224and the second intersection region223interposed therebetween, and more specifically, the pair of second probes510may contact both ends of the third linear region221. The another pair of second probes510may also contact the fourth linear region222with the second welding region224and the second intersection region223interposed therebetween, and more specifically, the another pair of second probes510may contact both ends of the fourth linear region222.

In the first welding determining step S300, a state of the first welding may be determined based on the first resistance value and the second resistance value, and in the second welding determining step S400, a state of the second welding may be determined based on the third resistance value and the fourth resistance value. By combining the first resistance value and the second resistance value, an overall state of the first welding may be identified, and a welding state of a local region in the first welding region214may also be identified individually as an independent value as needed. By combining the third resistance value and the fourth resistance value, an overall state of the second welding may be identified, and a welding state of a local region in the second welding region224may also be identified individually as an independent value as needed.

As shown inFIG.4, the resistance measurement in the first measuring step S100and the second measuring step S200may be carried out by a 4-wire low-resistance direct current method. The anode probe and the cathode probe may include a terminal connected to an ammeter and a terminal connected to a voltmeter, respectively.

The method for inspecting a welding state of a battery of the present disclosure may need to accurately measure resistance values of 1Ω or less, and to this end, it may be preferable to utilize a 4-wire low-resistance direct current method which may minimize the influence of any wiring resistance or contact resistance.

As shown inFIG.8, in the method for inspecting a welding state of a battery of the present disclosure, an arc-shaped adhesive portion215may be provided on an edge of the first current collector plate210, and the cylindrical battery may further include a can housing310configured to house the jelly roll100inside, wherein the adhesive portion215is third welded to an inner perimeter surface of the can housing310; and an electrode terminal320fixed to a lower end of the can housing310with an insulator330interposed therebetween and fourth welded to the second current collector plate220.

The can housing310may have a cylindrical shape with an open upper end, and the jelly roll100may be inserted into the upper end. An opening311may be formed at a lower end of the can housing310such that the electrode terminal320may be exposed to the outside of the can housing310through the opening311while contacting with the second current collector220therein at the same time.

As shown inFIG.9, the method for inspecting a welding state of a battery of the present disclosure may further include:after the second welding determining step S400,a third measuring step S500of measuring a resistance value by contacting a probe with the first current collector plate210and contacting another probe with an outer perimeter surface of the can housing310;a fourth measuring step S600of measuring a resistance value by contacting a probe with the second current collector plate220and contacting another probe with the electrode terminal320;a third welding determination step S700of determining a state of the third welding based on the resistance value measured in the third measuring step S500; anda fourth welding determination step S800of determining a state of the fourth welding based on the resistance value measured in the fourth measuring step S600.

As shown inFIG.10, in the third measuring step S500, a resistance value may be measured by contacting a probe with the first current collector plate210and contacting another probe with an outer perimeter surface of the can housing310. In the third measuring step S500, the cathode probe and the anode probe may be disposed such that the first welding region214is not located between the cathode probe and the anode probe.

As shown inFIG.11, a resistance value may be measured by contacting a probe with the second current collector plate220and contacting another probe with the electrode terminal320. Specifically, the resistance value may be measured by contacting a probe with the upper surface of the second current collector plate220through a central tube150located on a central axis of the jelly roll100, and contacting another probe with a lower end of the electrode terminal320from the outside of the can housing.

In the third measuring step S500and the fourth measuring step S600, the resistance measurement may also be carried out by a 4-wire low-resistance direct current method.

A method for manufacturing a battery using the method for inspecting a welding state of a battery of the present disclosure may include:a jelly roll100forming step of forming a jelly roll100by winding a sequential stack of the first current collector110, the first separator130, the second current collector120, and the second separator140;a first welding step of first welding the first current collector110and the first current collector plate210at an upper end of the jelly roll100;a second welding step of second welding the second current collector120and the second current collector plate220at a lower end of the jelly roll100;a first welding determining step of measuring resistance by contacting a first probe unit400with an upper surface of the first current collector plate210and determining a state of the first welding based on the measured resistance value;a second welding determining step of measuring resistance by contacting a second probe unit500with a lower surface of the second current collector plate220and determining a state of the second welding based on the measured resistance value;a third welding step of third welding the first current collector plate210and the can housing310;a fourth welding step of fourth welding the second current collector plate220and the electrode terminal320;a third welding determining step of measuring resistance by contacting a probe with the first current collector plate210and contacting another probe with an outer perimeter surface of the can housing310, and determining the third welding state based on the measured resistance value;a fourth welding determining step of measuring resistance by contacting a probe with the second current collector plate220and contacting another probe with the electrode terminal320, and determining the fourth welding state based on the measured resistance value; anda sealing step of injecting an electrolyte into the can housing310and sealing the can housing310.

According to the method for manufacturing a battery of an example embodiment, resistance values of welding sites are measured in-between each process, and the corresponding welding states are identified immediately, thereby preventing defective products from proceeding to the final process in advance, and inspecting welding states of each part individually without destroying the battery.

Although the example embodiments according to the present disclosure have been described above, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent ranges of the example embodiments are possible therefrom. Accordingly, the scope for true technical protection of the present disclosure should be defined by the appended claims.

INDUSTRIAL APPLICABILITY

According to a method for inspecting a welding state of a battery of example embodiments of the present disclosure, it is possible to perform in-line total inspection, thereby improving the quality of battery production and removing defective batteries in advance.

According to a method for inspecting a welding state of a battery of example embodiments of the present disclosure, it is possible to identify welding qualities within a short time period.