Patent Description:
A three-electrode analysis system using a reference electrode is mainly used for the cathode/anode separation analysis of a secondary battery. In a conventional three-electrode system, a thin copper wire coated with an LTO (Li<NUM>Ti<NUM>O<NUM>) active material is used as a reference electrode.

Specifically, as shown in <FIG>, in the three-electrode battery, a Cu wire coated with an LTO active material may be inserted as a reference electrode <NUM> into a separator <NUM> stacked between a cthode <NUM> and an anode <NUM>. More specifically, the separator <NUM> between the cathode <NUM> and the anode <NUM> is provided in two layers, and the reference electrode <NUM> may be located between the two layers of the separator <NUM>.

At this time, when a wire-type reference electrode is used, as shown in <FIG>, due to the shape of the reference electrode <NUM>, a blocking area is generated, and thus an unreacted area is formed, making it difficult to perform accurate cathode/anode separation analysis.

Depending on the stiffness or thickness of the electrode itself, the size of the blocking area may be enlarged and become a problem, and in particular, when the pressure increases in the area where the reference electrode is located due to the increase in the internal pressure of the battery due to the increase in the thickness of the electrode and the generation of gas generated while the battery is operating, damage to the electrode and the separator may occur.

Therefore, there is a need for a technology for a battery or system capable of stable three-electrode analysis regardless of the electrode's own properties and whether or not the electrode is operated.

<CIT> relates to a method of estimating a battery charge limit in order not to cause Li-plating, and a battery charging method and apparatus capable of quickly charging the battery are provided. The method for estimating a battery charge limit according to the present invention includes (a) a step of fabricating a three electrode cell having a unit cell and a reference electrode; (b) a step of measuring an anode potential (CCV) according to SOC while charging the three electrode cell; and (c) a step of setting a point at which a negative electrode potential starts to become constant without falling, as a point of occurrence of Li-plating, and setting it as a charging limit.

<CIT> discloses a battery management systems with control logic for battery state estimation (BSE), methods for making/using/assembling a battery cell with a reference electrode, and electric drive vehicles equipped with a traction battery pack and BSE capabilities. The battery cell assembly includes a battery housing with an electrolyte composition stored within the battery housing. The electrolyte composition transports ions between working electrodes. A first working (anode) electrode is attached to the battery housing in electrochemical contact with the electrolyte composition. Likewise, a second working (cathode) electrode is attached to the battery housing in electrochemical contact with the electrolyte composition. A reference electrode is interposed between the first and second working electrodes, placed in electrochemical contact with the electrolyte composition. The reference electrode and one or both working electrodes cooperate to output a half-cell voltage signal that is indicative of a battery state of the battery cell assembly.

<CIT> provides a three-electrode battery and a preparation method thereof. The preparation method comprises the following steps: first tabs are connected to a positive tab and a negative tab of a charged battery cell body respectively, and the first tabs are partially exposed out of a battery shell; a reference electrode is coated with a diaphragm and connected with a second tab, part of the second tab is exposed out of the battery shell, the diaphragm is arranged in the battery shell, and the reference electrode and the charged battery cell body are kept in a non-contact state; and the three-electrode battery is packaged, then electrolyte is injected, and the injection coefficient of the electrolyte is <NUM>-<NUM>/Ah; and then shelving aging and secondary sealing processes are carried out to finish the preparation of the three-electrode battery.

The present disclosure relates to a three-electrode battery and a performance analysis system using the same, and is to provide a three-electrode battery in which electrode pitting and internal short circuits are suppressed, and a performance analysis system using the same.

The technical problems to be achieved by the present disclosure are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description below.

A three-electrode battery of the present disclosure includes.

A performance analysis system of the present disclosure using the three-electrode battery of the present disclosure includes.

According to a three-electrode battery and a performance analysis system using the same of the present disclosure, it is possible to minimize the area of the blocking area due to the reference electrode, and suppress occurrence of circuit problems such as internal short circuit or electrode damage such as electrode pitting due to changes in battery internal pressure.

The three-electrode battery of the present disclosure and performance analysis system using the same may be capable of highly reliable separation analysis of the cathode/anode regardless of the electrode's own physical properties and whether or not the electrode is operated.

The three-electrode battery of the present disclosure may be advantageous for analysis of Si/SiO batteries with significant thickness changes or long-term degradation analysis.

In the three-electrode battery of the present disclosure, an effect of reducing three-electrode deviation can be expected due to the reduction of the blocking area.

The three-electrode battery of the present disclosure has a structure that is easy to design for a medium or large-sized battery, and can be applied regardless of the stack or area of electrodes.

The three-electrode battery of the present disclosure may further include a reference electrode lead (<NUM>) having one end fused to the second region (A2) of the reference electrode (<NUM>) and the other end protruding out of the battery case (<NUM>).

In the three-electrode battery of the present disclosure, the first electrode (<NUM>) or the second electrode (<NUM>) may be provided in a rectangular shape having a first direction and a second direction orthogonal to each other as corners, when a length of the first electrode or the second electrode in the first direction is formed to be longer than a length in the second direction, a length (Wr) of the first region (A1) in the first direction may be formed to be <NUM>% to <NUM>% of the length (FL) of the first electrode (<NUM>) or the second electrode (<NUM>) in the first direction, and a length (Lr) of the first region (A1) in the second direction may be formed to be <NUM>% to <NUM>% of the length (Fw) of the first electrode (<NUM>) or the second electrode (<NUM>) in the second direction.

In the three-electrode battery of the present disclosure, the reference electrode (<NUM>) may include a foil member (<NUM>) forming a body of the reference electrode, and a reference electrode active material (<NUM>) coated on the foil member (<NUM>).

In the three-electrode battery of the present disclosure, a material of the foil member (<NUM>) may include at least one of Cu-foil and Al-foil.

In the three-electrode battery of the present disclosure, the reference electrode active material (<NUM>) may be selected from LTO (Li<NUM>Ti<NUM>O<NUM>), LFP (LiFePO<NUM>), Li metal, and combinations thereof.

Hereinafter, with reference to the accompanying drawings, embodiments according to the present disclosure will be described in detail. In this process, the size or shape of the components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, in consideration of the configuration and operation of the present disclosure, specially defined terms may vary depending on the intentions or practices of users and operators. Definitions of these terms should be based on the content throughout this specification.

In the description of the present disclosure, it should be noted that an orientation or positional relationship indicated by the terms "center", "top", "bottom", "left", "right", "vertical", "horizontal", "inside", "outside", "one side", "other side", and the like, is based on an orientation or positional relationship shown in the drawings, or an orientation or positional relationship that is usually placed when using a product of the present disclosure, and is intended only for explanation and brief description of the present disclosure, and is not to be construed as limiting the present disclosure because it does not suggest or imply that a device or element shown should necessarily be configured or operated in a specific orientation with a specific orientation.

<FIG> is a cross-sectional view illustrating a three-electrode battery of the present disclosure. <FIG> is an exploded perspective view illustrating a stacked structure of a three-electrode battery of the present disclosure. <FIG> is a plan view illustrating a disposition relationship between a first electrode <NUM> and a reference electrode <NUM>. <FIG> is a graph illustrating battery characteristics according to an open ratio of a first region <NUM>. <FIG> are photographs illustrating a state of a battery electrode according to the reference electrode <NUM>. <FIG> is a graph illustrating charging depth at 1C charge and 2C charge.

Hereinafter, the three-electrode battery of the present disclosure will be described in detail with reference to <FIG>. In the xyz coordinate system shown in <FIG>, an x-axis direction may be a first direction, a y-axis direction may be a second direction, and a z-axis direction may be a vertical direction.

The three-electrode battery of the present disclosure can be applied to various types of batteries, but may be optimized for a pouch type battery.

As shown in <FIG>, the three-electrode battery of the present disclosure includes.

One of the first electrode <NUM> and the second electrode <NUM> may be formed as a cathode, and the other may be formed as an anode.

As shown in <FIG>, the first electrode <NUM> may include a first electrode current collector <NUM>, a first electrode active material <NUM> applied to the surface of the first electrode current collector <NUM>, a first electrode tab <NUM> welded to an uncoated portion of the first electrode current collector <NUM> on which the first electrode active material <NUM> is not coated, and a first electrode lead <NUM> having one end welded to the first electrode tab <NUM> inside the battery case <NUM> and the other end protruding out of the battery case <NUM>. The second electrode <NUM> may also include a second electrode current collector <NUM>, a second electrode active material <NUM> applied to the surface of the second electrode current collector <NUM>, a second electrode tab <NUM> welded to an uncoated portion of the second electrode current collector <NUM> on which the second electrode active material <NUM> is not coated, and a second electrode lead <NUM> having one end welded to the second electrode tab <NUM> inside the battery case <NUM> and the other end protruding out of the battery case <NUM>.

The material of the main separator <NUM> and auxiliary separator <NUM> may include at least one of ethylene homopolymer, propylene homopolymer, ethylene/butene copolymer, ethylene/hexene copolymer, and ethylene/methacrylate copolymer.

The main separator <NUM> may be located between the first electrode <NUM> and the second electrode <NUM>.

The main separator <NUM>, the first electrode <NUM>, and the second electrode <NUM> may be provided in plurality, respectively, and in this case, the auxiliary separator <NUM> and the reference electrode <NUM> may be provided on one of the plurality of main separators <NUM>.

Each of the main separator <NUM>, the first electrode <NUM>, and the second electrode <NUM> may be provided in a sheet shape and stacked so as to cross each other.

The auxiliary separator <NUM> may be formed in a size capable of covering the reference electrode <NUM> so that the reference electrode <NUM> does not directly contact the first electrode <NUM> or the second electrode <NUM>.

As shown in <FIG>, the three-electrode battery of the present disclosure may be completed by injecting an electrolyte together with an electrode assembly formed by stacking the second electrode <NUM>, the main separator <NUM>, the reference electrode <NUM>, the auxiliary separator <NUM>, and the first electrode <NUM> in this order, or the first electrode <NUM>, the auxiliary separator <NUM>, the reference electrode <NUM>, the main separator <NUM>, and the second electrode <NUM> in this order into the battery case <NUM> and then sealing the battery case <NUM>.

At this time, when the first electrode <NUM> and the second electrode <NUM> are provided in plurality, respectively, the first electrode tab <NUM> welded to each of the plurality of first electrodes <NUM> may be welded to one first electrode lead <NUM>, the second electrode tab <NUM> welded to each of the plurality of second electrodes <NUM> may be welded to one second electrode lead <NUM>, and one end of the first electrode lead <NUM> and one end of the second electrode lead <NUM> may protrude out of the battery case <NUM>.

In the three-electrode battery of the present disclosure, the reference electrode <NUM> has a plurality of perforated holes <NUM> formed therein. By forming a plurality of perforated holes <NUM> in the reference electrode <NUM>, it is possible to prevent the reference electrode <NUM> from interfering with the movement of ions between the first electrode <NUM> and the second electrode <NUM> and suppress the formation of a blocking area.

As shown in <FIG> and <FIG>, the reference electrode <NUM> includes a first region A1 facing the first electrode <NUM> or the second electrode <NUM>, and a second region A2 protruding from one side of the first electrode <NUM> or the second electrode <NUM>, wherein the plurality of perforated holes <NUM> are formed in the first region A1. In other words, the first region A1 may be used to establish a standard for the potential applied to the first electrode <NUM> or the second electrode <NUM>, and the second region A2 may be used for electrical connection.

The total area of the plurality of perforated holes <NUM> may be formed to be <NUM>% to <NUM>% of the area of the first region A1. In other words, the total area of the plurality of perforated holes <NUM> may be formed to be <NUM>% to <NUM>% of the area of the first region A1. When the open ratio is <NUM>% or less in the first region A1, ion diffusion may not be smooth, and when it is <NUM>% or more, the reference electrode may be broken. Therefore, the open ratio formed by the plurality of perforated holes <NUM> in the first region A1 may be preferably <NUM>% to <NUM>%.

<FIG> is a graph illustrating battery characteristics according to an open ratio of a first region. Specifically, for a battery including an electrode assembly stacked in the order of a cathode, a separator, and an anode, it is a graph showing battery characteristics according to the open ratio of the test foil after inserting a test foil having a perforated hole between the separator and the anode. Four batteries were prepared, and test foils having open ratio of <NUM>%, <NUM>%, and <NUM>% were inserted into three batteries, respectively, and the test foil was not inserted into the other battery. As shown in <FIG>, it can be seen that while the battery provided with the test foil having less than <NUM>% open ratio (<NUM>% open ratio) appear to have impaired ion migration, the battery provided with the test foil having an open ration of <NUM>% or more (<NUM>% and <NUM>% open ratio) exhibits behavior similar to that of the secondary battery without the test foil itself.

The three-electrode battery of the present disclosure may further include a reference electrode lead <NUM> having one end fused to the second region A2 of the reference electrode <NUM> and the other end protruding out of the battery case <NUM>. Since the reference electrode <NUM> may be formed of a thin metal film or foil, it may not be fused to seal the battery case <NUM> or have minimal rigidity for connection to an external electric terminal. Accordingly, the reference electrode lead <NUM>, which is a conductor for electrical connection, may be connected to the reference electrode <NUM>, and the reference electrode lead <NUM> may be welded to the second region A2.

The reference electrode <NUM> may be provided with a thickness of <NUM> to <NUM>. The thickness of the reference electrode <NUM> may be determined in consideration of a lifting phenomenon between the first electrode <NUM> and the second electrode <NUM>, a dent phenomenon caused by shock or vibration applied to the three-electrode battery itself, and the like.

As shown in <FIG>, in the three-electrode battery of the present disclosure, the first electrode <NUM> or the second electrode <NUM> may be provided in a rectangular shape having first and second directions orthogonal to each other as corners. More specifically, the length of the first electrode <NUM> or the second electrode <NUM> in the first direction may be longer than the length in the second direction.

At this time, the length Wr of the first region A1 in the first direction may be formed <NUM>% to <NUM>% of the length FL of the first electrode <NUM> or the second electrode <NUM> in the first direction, and the length Lr of the first region A1 in the second direction may be formed <NUM>% to <NUM>% of the length Fw of the first electrode <NUM> or the second electrode <NUM> in the second direction. The length Lr of the first region A1 in the second direction may be determined in consideration of specifications, materials, number of layers, and types of layers of the first electrode or the second electrode.

In other words, the reference electrode <NUM> may be provided in a shape extending in a direction perpendicular to the longitudinal direction of the first electrode <NUM> or the second electrode <NUM>.

As shown in <FIG>, the reference electrode <NUM> may include a foil member <NUM> forming a body and a reference electrode active material <NUM> coated on the foil member <NUM>. The reference electrode active material <NUM> may be applied to the first region A1, and the second region A2 may be formed as an uncoated portion where the reference electrode active material <NUM> is not applied. For example, the width of the first region A1 and the second region A2 in the first direction may be formed <NUM>, and the length in the second direction may be formed <NUM> for the first region A1 and <NUM> for the second region A2.

The material of the foil member <NUM> may include at least one of Cu-foil and Al-foil, and the reference electrode active material <NUM> may be selected from LTO (Li<NUM>Ti<NUM>O<NUM>), LFP (LiFePO<NUM>), Li metal, and combinations thereof.

The performance analysis system using the three-electrode battery of the present disclosure includes.

As the first electrode <NUM>, one of a cathode and an anode may be selected according to the analysis purpose.

<FIG> are photographs of electrode surfaces in a battery when the reference electrode <NUM> of the three-electrode battery of the present disclosure is applied and when a conventional wire-type reference electrode is applied. In <FIG>, on the left, a conventional wire-type reference electrode is applied, and on the right, the reference electrode <NUM> of the present disclosure is applied.

<FIG> is an electrode extracted from a battery with <NUM>% state of charge (SoC). It can be seen that the unreacted area is observed in the conventional type, but the electrode of the three-electrode battery of the present disclosure does not have an unreacted area.

<FIG> is an electrode extracted from a battery applied with 1C/1C, <NUM> cycles of charging and discharging. In the conventional type, it can be seen that Li precipitation is nonuniform in the vicinity of the wire-type reference electrode.

<FIG> is a photograph extracted from a battery dedicated to fast charge. In the conventional type, precipitation deepening occurs in the area adjacent to the wire-type reference electrode, but in the electrode of the three-electrode battery of the present disclosure, precipitation in the area adjacent to the reference electrode <NUM> is alleviated.

<FIG> is a graph illustrating charging depth at 1C charge and 2C charge. It can be seen that the three-electrode battery of the present disclosure has a reduced variation in charging depth compared to the conventional battery.

Reference electrode, <NUM>. Foil member, <NUM>. Reference electrode active material, <NUM>. Perforated hole, <NUM>. Reference electrode lead, <NUM>. Main separator, <NUM>. Auxiliary separator, <NUM>. First electrode, <NUM>. First electrode current collector, <NUM>. First electrode active material, <NUM>. First electrode tab, <NUM>. First electrode lead, <NUM>. Second electrode, <NUM>. Second electrode current collector, <NUM>. Second electrode active material, <NUM>. Second electrode tab, <NUM>. Second electrode lead, <NUM>. Battery case, A1. First region, A2. Second region.

According to a three-electrode battery and performance analysis system using the same of the present disclosure, it is possible to minimize the area of the blocking area due to the reference electrode, and suppress the occurrence of circuit problems such as internal short circuit or electrode damage such as electrode pitting due to changes in battery internal pressure.

The three-electrode battery of the present disclosure and a performance analysis system using the same may be capable of highly reliable separation analysis of the cathode/anode regardless of the electrode's own physical properties and whether or not it is operated.

In the three-electrode battery of the present disclosure, the effect of reducing the three-electrode deviation can be expected due to the reduction of the blocking area.

Claim 1:
A three-electrode battery comprising:
a main separator (<NUM>);
a film-shaped reference electrode (<NUM>) stacked on one side of the main separator (<NUM>);
an auxiliary separator (<NUM>) stacked on the one side of the main separator (<NUM>) with the reference electrode (<NUM>) interposed between the main separator (<NUM>) and the auxiliary separator (<NUM>);
a first electrode (<NUM>) and a second electrode (<NUM>) stacked with the main separator (<NUM>), the reference electrode (<NUM>), and the auxiliary separator (<NUM>) interposed therebetween; and
a battery case (<NUM>) in which the main separator (<NUM>), the reference electrode (<NUM>), the auxiliary separator (<NUM>), the first electrode (<NUM>), and the second electrode (<NUM>) are accommodated in an inner space of the battery case,
wherein the reference electrode (<NUM>) is formed with a plurality of perforated holes (<NUM>) and
wherein the reference electrode (<NUM>) comprises:
a first region (A1) facing the first electrode (<NUM>) or the second electrode (<NUM>); and
a second region (A2) protruding from one side of the first electrode (<NUM>) or the second electrode (<NUM>), and
wherein the plurality of perforated holes (<NUM>) are formed in the first region (a1).