Apparatus and method for generating a lithium iron phosphate battery model

Abstract

An apparatus and method for generating an LFP battery model are disclosed. The apparatus for generating an LFP battery model according to the present disclosure includes a lithium state recording unit that records a state of lithium (Li) in a positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery according to charging or discharging of the LFP battery, and a battery model generating unit that generates a battery model of the LFP battery based on the recorded state of lithium in the positive electrode active material, wherein the battery model generating unit can generate the battery model by modeling the LFP battery with a plurality of resistors and capacitors that reflect the state of lithium in the positive electrode active material.

Description

[0001] Cross-references to related applications

[0002] This application claims priority and benefit to Korean Patent Application No. 10-2024-0174220, filed on November 28, 2024, with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] Various aspects of embodiments of this disclosure relate to apparatus and methods for generating lithium iron phosphate (LiFePO4, LFP) battery models, and more specifically, to apparatus and methods for recording the state of lithium (Li) in the positive electrode active material of an LFP battery during charging or discharging, and for generating a battery model of an LFP battery based on the recorded state of lithium in the positive electrode active material. Background Technology

[0004] Unlike primary batteries, which are not designed for charging, secondary batteries are designed for discharging and recharging. Low-capacity secondary batteries are used in small portable electronic devices such as smartphones, feature phones, laptops, digital cameras, and camcorders, while high-capacity secondary batteries are widely used as power sources for motors in vehicles such as hybrid or electric vehicles, as well as for energy storage. A secondary battery includes an electrode assembly containing positive and negative electrodes, a housing that houses the electrode assembly, and terminals that connect to the electrode assembly.

[0005] Lithium-ion batteries are classified according to the material used to form the positive electrode active material. When classified by the positive electrode active material, there are "ternary" and "quaternary" batteries formed using lithium cobalt oxide (LCO) as the positive electrode active material, and "LFP batteries" formed using lithium iron phosphate (LiFePO4, LFP) as the positive electrode active material, which uses iron phosphate instead of cobalt. LFP batteries use inexpensive iron phosphate instead of expensive cobalt, thus reducing the price of raw materials introduced for battery manufacturing, and are stable due to the "olivine structure" formed in a hexagonal shape within the positive electrode active material structure. Therefore, LFP batteries have the advantages of a lower risk of accidents caused by overcharging and over-discharging, and a longer battery life due to less degradation of individual cells.

[0006] A battery pack comprising multiple battery cells may include a battery management system (BMS) that manages the multiple battery cells, such as monitoring the voltage, current, temperature, etc. of the multiple battery cells included in the battery pack.

[0007] There is a need to develop battery models to implement algorithms for calculating the state of charge (SOC), state of health (SOH), and other parameters of the battery used in the battery management system (BMS). However, the ECM (equivalent circuit model) method used alone in existing ternary systems cannot reflect the unique characteristics of the LFP (cell power factor) whose internal resistance varies depending on the charging and discharging paths. Therefore, existing ECM methods increase the error of the battery model, ultimately leading to increased errors in SOC and SOH.

[0008] The information disclosed in this background section is intended to enhance the understanding of the background of this disclosure, and therefore may contain information that does not constitute related (or prior art). Summary of the Invention

[0009] This disclosure is made in view of the foregoing, and is intended to provide an apparatus and method for recording the state of lithium (Li) in the positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery during charging or discharging of an LFP battery, and for generating a battery model of an LFP battery based on the recorded state of lithium in the positive electrode active material.

[0010] However, the technical problems to be solved by this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the description of this disclosure other problems not mentioned herein, as well as aspects and features of this disclosure that will solve these problems.

[0011] An apparatus for generating an LFP battery model according to an embodiment of the present disclosure includes: a lithium state recording unit that records the state of lithium (Li) in the positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery being charged or discharged according to the LFP battery; and a battery model generating unit that generates a battery model of the LFP battery based on the recorded state of lithium in the positive electrode active material, wherein the battery model generating unit can generate the battery model by modeling the LFP battery with a plurality of resistors and capacitors reflecting the state of lithium in the positive electrode active material.

[0012] In an embodiment, the lithium state recording unit can record the distribution of lithium from the peripheral portion to the center in the positive electrode active material of the LFP battery, which varies depending on the charging or discharging of the LFP battery.

[0013] In an embodiment, the battery model generation unit can generate a battery model of an LFP battery in the form of including a first resistor and a second resistor in an equivalent circuit model (ECM).

[0014] In an embodiment, the battery model generation unit can generate a battery model of an LFP battery by dividing the state of lithium into a first case and a second case. In the first case, when the LFP battery is charged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery. In the second case, when the LFP battery is charged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

[0015] In an embodiment, in the first case generated in the battery model generation unit, the first resistor may be a drop resistor that takes into account the voltage difference between the voltage of the LFP battery measured according to at least one of state of charge (SOC), charge and discharge rate (c-rate) and temperature and the open circuit voltage (OCV) according to at least one of SOC and temperature, and the second resistor may be 0.

[0016] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the LFP battery measured according to at least one of SOC, charge and discharge rate and temperature is V_measurement(soc, c-rate, temp), the OCV according to at least one of SOC and temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rate is I_c-rate, and the first resistor is R_a, the first resistor R_a can be calculated by the following equation.

[0017]

[0018] In an embodiment, in the second case generated in the battery model generation unit, the first resistance can be 0, and the second resistance can have a resistance value obtained by reflecting the distribution state of lithium in the positive electrode active material of the LFP battery in the voltage drop resistance, which varies depending on the SOC.

[0019] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the nearest lithium distribution start point to the periphery in the positive electrode active material of the LFP battery according to the SOC is K_a(soc), the nearest lithium distribution end point to the periphery in the positive electrode active material of the LFP battery at the start of charging after the discharge state or the rest state after discharge is K_b_captured, and the second resistor is R_b, the second resistor R_b can be calculated by the following equation.

[0020]

[0021] In an embodiment, the battery model generation unit can generate a battery model of an LFP battery by dividing the state of lithium into a third case and a fourth case. In the third case, when the LFP battery is discharged, lithium is not distributed in the peripheral part of the positive electrode active material of the LFP battery. In the fourth case, when the LFP battery is discharged, lithium is distributed in the peripheral part of the positive electrode active material of the LFP battery.

[0022] In an embodiment, in the fourth case generated in the battery model generation unit, the first resistor may be 0, and the second resistor may be a voltage drop resistor that takes into account the voltage difference between the voltage of the LFP battery measured according to at least one of state of charge (SOC), charge and discharge rate (c-rate) and temperature, and the open circuit voltage (OCV) according to at least one of SOC and temperature.

[0023] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the LFP battery measured according to at least one of SOC, charge and discharge rate, and temperature is V_measurement(soc, c-rate, temp), the OCV according to at least one of SOC and temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rate is I_c-rate, and the second resistor is R_b, the second resistor R_b can be calculated by the following equation.

[0024]

[0025] In an embodiment, in the third case generated in the battery model generation unit, the first resistor may have a resistance value obtained by reflecting the distribution state of lithium in the positive electrode active material of the LFP battery in the voltage drop resistor, the distribution state varying depending on the SOC, and the second resistor may be 0.

[0026] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the nearest lithium distribution endpoint to the periphery in the positive electrode active material of the LFP battery according to the SOC is K_b(soc), the nearest lithium distribution starting point to the periphery in the positive electrode active material of the LFP battery at the moment of discharge start after the charging state or the resting state after charging is Ka_a_captured, and the first resistor is R_a, the first resistor R_a can be calculated by the following equation.

[0027]

[0028] A method for generating an LFP battery model according to an embodiment of the present disclosure includes: a lithium state recording step, which records the state of lithium (Li) in the positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery being charged or discharged according to an LFP battery in a lithium state recording unit; and a battery model generation step, which generates a battery model of the LFP battery in a battery model generation unit based on the recorded state of lithium in the positive electrode active material, wherein the battery model generation step may include a step of generating a battery model by modeling the LFP battery with a plurality of resistors and capacitors reflecting the state of lithium in the positive electrode active material.

[0029] In an embodiment, the lithium state recording step may include recording the distribution of lithium from the periphery to the center in the positive electrode active material of the LFP battery, which varies depending on whether the LFP battery is being charged or discharged.

[0030] In an embodiment, the battery model generation step may include generating a battery model of the LFP battery in a form that includes a first resistor and a second resistor in an equivalent circuit model (ECM).

[0031] In an embodiment, the battery model generation step may further include generating a battery model of an LFP battery by dividing the state of lithium into a first case and a second case, wherein in the first case, when the LFP battery is charged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery, and in the second case, when the LFP battery is charged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

[0032] In an embodiment, in the first case generated during the battery model generation step, the first resistor may be a drop resistor considering a voltage difference between the voltage of the LFP battery measured according to at least one of state of charge (SOC), charge and discharge rate (c-rate), and temperature, and an open-circuit voltage (OCV) based on at least one of SOC and temperature, and the second resistor may be 0. In the second case generated during the battery model generation step, the first resistor may be 0, and the second resistor may have a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the LFP battery in the drop resistor, the distribution varying depending on the SOC.

[0033] In an embodiment, the battery model generation step may further include generating a battery model of an LFP battery by dividing the state of lithium into a third case and a fourth case, wherein in the third case, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery when the LFP battery is discharged, and in the fourth case, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery when the LFP battery is discharged.

[0034] In an embodiment, in the fourth case generated during the battery model generation step, the first resistance may be 0, and the second resistance may be a voltage drop resistor considering a voltage difference between the voltage of the LFP battery measured according to at least one of state of charge (SOC), charge and discharge rate (c-rate), and temperature, and an open-circuit voltage (OCV) based on at least one of SOC and temperature. In the third case generated during the battery model generation step, the first resistance may have a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the LFP battery in the voltage drop resistor, the distribution varying depending on the SOC, and the second resistance may be 0.

[0035] According to embodiments of this disclosure, by recording the state of lithium (Li) in the positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery during charging or discharging of an LFP battery, and generating a battery model of an LFP battery based on the recorded state of lithium in the positive electrode active material, it is possible to record how the state of lithium in the positive electrode active material changes depending on the history of previous charging and discharging paths, and to define how the internal resistance changes depending on the current internal state of the positive electrode reflecting the history of previous charging and discharging paths, and these can ultimately be applied to the battery model.

[0036] According to embodiments of this disclosure, by generating a battery model that reflects the internal state of the positive electrode active material (which varies depending on the history of previous charging and discharging paths), accuracy can be increased by reducing errors in the battery model, and thus, errors in the state of charge (SOC) and state of health (SOH) of the battery calculated from the BMS can be reduced.

[0037] However, the aspects and features of this disclosure are not limited to those described herein, and those skilled in the art will clearly understand from the detailed description herein that other aspects and features are not mentioned. Attached Figure Description

[0038] The following accompanying drawings illustrate embodiments of the present disclosure, and together with the detailed description of the present disclosure, aspects and features of the present disclosure are further described. Therefore, the present disclosure should not be construed as limited to the drawings:

[0039] Figure 1 This is a schematic diagram illustrating a cylindrical lithium secondary battery according to an embodiment;

[0040] Figure 2 This is a schematic diagram illustrating a prismatic lithium secondary battery according to an embodiment;

[0041] Figure 3 and Figure 4 Each of these is a schematic diagram illustrating a pouch-type lithium secondary battery according to an embodiment;

[0042] Figure 5 A battery model represented using the existing ECM (Equivalent Circuit Model) method is shown;

[0043] Figure 6 This is a diagram illustrating an example of how the resistance value varies depending on the charging path of the LFP battery;

[0044] Figure 7 This is a schematic diagram illustrating an apparatus for generating an LFP battery model according to an embodiment of the present disclosure;

[0045] Figure 8 This is a diagram illustrating a method for recording the state of lithium in the positive electrode active material of an LFP battery using a lithium state recording unit of an apparatus for generating an LFP battery model according to embodiments of the present disclosure.

[0046] Figure 9 An example is shown of a lithium state recording unit of an apparatus for generating an LFP battery model according to an embodiment of the present disclosure, which records the state of lithium in the positive electrode active material of an LFP battery.

[0047] Figure 10 This is a diagram illustrating an example of the state of lithium in the positive electrode active material of an LFP battery recorded by a lithium state recording unit in an apparatus for generating an LFP battery model according to an embodiment of the present disclosure, during charging of the LFP battery.

[0048] Figure 11 This is a diagram illustrating an example of the state of lithium in the positive electrode active material of an LFP battery recorded by a lithium state recording unit in an apparatus for generating an LFP battery model according to an embodiment of the present disclosure during the discharge of the LFP battery.

[0049] Figure 12 This is a diagram illustrating an example of a battery model generated by a battery model generation unit of an apparatus for generating an LFP battery model according to an embodiment of the present disclosure;

[0050] Figure 13 and Figure 14This is a diagram illustrating an example of a battery model generation unit of an apparatus for generating an LFP battery model according to an embodiment of the present disclosure, which generates a battery model based on the state of lithium in the positive electrode active material of the LFP battery recorded by a lithium state recording unit during charging of the LFP battery.

[0051] Figure 15 and Figure 16 This is a diagram illustrating an example of a battery model generation unit in an apparatus for generating an LFP battery model according to embodiments of the present disclosure, where the battery model generation unit generates a battery model based on the state of lithium in the positive electrode active material of the LFP battery, as recorded by a lithium state recording unit during the discharge of the LFP battery; and

[0052] Figure 17 This is a flowchart describing a method for generating an LFP battery model according to embodiments of the present disclosure. Detailed Implementation

[0053] This document will describe exemplary embodiments of the present disclosure in detail with reference to the accompanying drawings. Before description, it should be noted that the terms or words used in this specification and claims should not be construed as limited to their ordinary or dictionary meanings, but should be understood to have meanings and concepts consistent with the spirit of this disclosure, based on the inventor's ability to appropriately define the concept of each term in order to best describe the principles of his / her own disclosure. Therefore, since the embodiments described in this specification and the configurations shown in the drawings are merely examples of this disclosure and do not cover all the technical ideas of this disclosure, it should be understood that various changes and modifications can be made at the time of filing this application.

[0054] It will be further understood that the term “comprising / including” as used herein specifies the presence of the stated features, numbers, steps, operations, elements, components and / or groups thereof, but does not exclude the presence or addition of one or more other features, numbers, steps, operations, elements, components and / or groups thereof.

[0055] For ease of understanding of this disclosure, the drawings are not drawn to scale, and the dimensions of some components may be exaggerated. It should be noted that the same reference numerals denote the same components in different embodiments.

[0056] Referring to two compared elements, features, etc., as “identical” means that they are “substantially identical.” Therefore, the phrase “substantially identical” can include what is considered a low deviation in the art, for example, 5% or less. The uniformity of any parameter in a given region can mean that it is uniform from an average perspective.

[0057] Although terms such as "first" and / or "second" are used to describe various components, these components are of course not limited by these terms. These terms are only used to distinguish one component from another. Therefore, unless specifically stated to the contrary, a first component may be referred to as a second component without departing from the teachings of the exemplary embodiments.

[0058] Throughout this specification, unless otherwise stated, each element may be singular or plural.

[0059] The arrangement of any component "above (or below)" or "on (or below)" a component can mean that any component is configured to contact the upper (or lower) surface of the component, and that other components may be inserted between the component and any components arranged on (or below) the component.

[0060] It should be understood that when a component is referred to as “connected,” “coupled,” or “joined” to another component, it can be directly “connected,” “coupled,” or “joined” to another component, or indirectly “connected,” “coupled,” or “joined” to another component, with other components interposed between them.

[0061] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. The use of “may” in describing embodiments of this disclosure refers to “one or more embodiments of this disclosure.” Expressions such as “at least one” and “one or more” preceding the list of elements modify the entire list of elements, but not the individual elements in the list.

[0062] Throughout the specification, when “A and / or B” is stated, it means A, B, or A and B, unless otherwise stated. Additionally, when “C to D” is stated, it means C or more and D or fewer, unless otherwise specifically stated.

[0063] When phrases such as “at least one of A, B and C”, “at least one of A, B or C”, “at least one of the group selected from A, B and C” or “at least one of A, B and C” are used to specify a list of elements A, B and C, the phrase may refer to any and all suitable combinations.

[0064] The term “use” may be considered synonymous with the term “utilization”. As used herein, the terms “substantially,” “about,” and similar terms are used as approximations rather than terms of degree and are intended to explain the inherent variations in measured or calculated values ​​that will be recognized by one of ordinary skill in the art.

[0065] It should be understood that although the terms first, second, third, etc., may be used herein to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of exemplary embodiments, the first element, component, area, layer, or portion discussed herein may be referred to as the second element, component, area, layer, or portion.

[0066] To facilitate explanation in describing the relationship between one element or feature and another element or feature as shown in the accompanying drawings, spatial relative terms such as "below," "below," "below," "above," and "above" are used herein. It should be understood that, in addition to the directions depicted in the accompanying drawings, spatial relative positions are intended to cover different orientations of the device in use or operation. For example, if the device in the accompanying drawings is flipped, any element described as "below" or "below" another element would be oriented as "above" or "above" another element. Therefore, the term "below" can cover both upward and downward directions.

[0067] The terminology used herein is for the purpose of describing embodiments of this disclosure and is not intended to limit the disclosure.

[0068] Secondary batteries include coin-shaped, cylindrical, prismatic, and pouch-shaped types. Before describing embodiments of this disclosure, cylindrical and prismatic secondary batteries will be described in general terms, as this disclosure can be applied substantially to cylindrical and prismatic secondary batteries.

[0069] Figures 1 to 4 This is a schematic diagram illustrating a lithium secondary battery according to an embodiment. Figure 1 A cylindrical lithium secondary battery can be shown. Figure 2 A prismatic lithium secondary battery can be shown. Figure 3 and Figure 4 A pouch-type lithium secondary battery can be shown. (Reference) Figures 1 to 4 A lithium secondary battery may include an electrode assembly 40 and a housing 50. In the electrode assembly 40, a separator 30 is inserted between a first electrode plate 10 and a second electrode plate 20. In the housing 50, the electrode assembly 40 is embedded. The first electrode plate 10, the second electrode plate 20, and the separator 30 may be impregnated in an electrolyte (not shown). Figure 1 As shown, a lithium secondary battery may include a sealing member 60 of a sealed housing 50. Furthermore, in Figure 2 In this lithium secondary battery, a first electrode lead connector 11, a first electrode terminal 12, a second electrode lead connector 21, and a second electrode terminal 22 may be included. For example... Figure 3 and Figure 4 As shown, the lithium secondary battery may include electrode terminals 70, namely, a first electrode terminal 71 and a second electrode terminal 72, which serve as an electrical path for guiding the current formed in the electrode assembly 40 toward the outside.

[0070] The electrode assembly 40 can be formed by winding or stacking a stack body including a first electrode plate 10, a second electrode plate 20, and a diaphragm 30, each of which is formed in an electrode plate shape or a film shape. In the case of a wound stack body, the winding axis of the electrode assembly 40 can be parallel to the length direction of the housing. Furthermore, the electrode assembly 40 can be stacked rather than wound, but the shape of the electrode assembly 40 is not limited in the embodiments disclosed herein. The first electrode plate 10 of the electrode assembly 40 can function as a positive electrode, and its second electrode plate 20 can function as a negative electrode, and vice versa.

[0071] The first electrode plate 10 can be formed by coating a first electrode active material (such as graphite or carbon) onto a first electrode current collector plate formed of metal foil (such as copper, copper alloy, nickel or nickel alloy), and may include a first electrode terminal (or a first uncoated portion), i.e., the area that has not yet been coated with the first electrode active material.

[0072] The second electrode plate 20 can be formed by coating a second electrode active material (such as a transition metal oxide) onto a material formed of a metal foil (such as aluminum or an aluminum alloy), and may include a second electrode tab (or a second uncoated portion), i.e., an area that has not yet been coated with the second electrode active material.

[0073] The separator 30 can be used to prevent short circuits between the first electrode plate 10 and the second electrode plate 20, while allowing lithium ions to move. The separator 30 may, for example, include a polyethylene membrane, a polypropylene membrane, or a polyethylene-polypropylene membrane.

[0074] It has been passed Figures 1 to 4 As an example, multiple secondary batteries can be gathered to form multiple battery cells and housed in a battery casing. The battery casing according to embodiments of this disclosure may include a support portion that supports the hook after the hook and hook hole are secured, and can maintain the hook and hook hole in a secured state, thus preventing the hook from breaking away due to retreat when an impact is applied to the battery pack. Hereinafter, a battery casing and a method of manufacturing a battery casing according to embodiments of this disclosure are described with reference to the accompanying drawings.

[0075] Figure 5A battery model is shown, represented in the existing ECM (Equivalent Circuit Model) manner.

[0076] refer to Figure 5 A battery model represented using the existing ECM approach can be described as a series resistor (Rs), a parallel resistor (Rp), and a parallel capacitor (Cp). The series resistor (Rs) is used to simulate the voltage drop when a load is connected and the voltage rise during charging. The parallel resistor (Rp) and parallel capacitor (Cp) are used to simulate the dynamic voltage response of the battery immediately following the voltage drop. Since the existing ternary system does not have path dependence, the resistance and capacitor values ​​in the model do not need to include previous charging and discharging history. Therefore, the existing ECM-type battery model can be used to fully simulate the battery.

[0077] However, as a unique property of LFP batteries, their internal resistance varies depending on the charging and discharging paths. For example, when an LFP battery at 100% state of charge (SOC) is discharged to 50% SOC, and when an LFP battery at 0% SOC is charged to 50% SOC, both LFP batteries have the same 50% SOC, but they have different charging and discharging paths to reach 50% SOC. This results in differences in the distribution of lithium (Li) ions in the positive electrode active material, and these differences cause differences in internal resistance, thus resulting in different internal resistance values.

[0078] Therefore, when the battery model represented by the existing ECM method is used for LFP batteries, the problem is that when the parameters of the series resistance (Rs), parallel resistance (Rp) and parallel capacitor (Cp) are set based on specific charging and discharging paths, all differences in the internal resistance values ​​caused by other charging or discharging paths are manifested as errors.

[0079] Figure 6 This is a diagram illustrating an example of how the resistance value varies depending on the charging path of the LFP battery.

[0080] refer to Figure 6 The graphs showing the voltage change over time are shown for cases where the SOC value increases from 40% to 60%, decreases from 45% to 40% and then increases back to 60%, and decreases from 50% to 40% and then increases back to 60%.

[0081] like Figure 6As shown, the voltage shows the steepest increase when the SOC value increases from 40% to 60%, a slightly gentler increase when the SOC value decreases from 45% to 40% and then increases again to 60%, and the gentlest increase when the SOC value decreases from 50% to 40% and then increases again to 60%.

[0082] This is because the internal resistance value varies depending on the charging and discharging path of the LFP battery, and this difference causes a difference in the voltage rise curve. Therefore, with Figure 5 The problem with existing ECM-based battery models is that errors occur in all charging and discharging paths in all other cases, even when parameters are set based on curves of any charging and discharging path.

[0083] Therefore, when attempting to apply the ECM model to LFP batteries, it is necessary to supplement the parameters reflecting the charging and discharging paths of the LFP battery. According to the apparatus and method for generating an LFP battery model according to embodiments of this disclosure, the internal resistance values ​​that change depending on the charging and discharging paths can be fully reflected in the battery model; therefore, regardless of... Figure 6 The battery model can be generated by determining which charging and discharging path the three curves follow. Therefore, accuracy can be improved by reducing errors in the battery model.

[0084] Figure 7 This is a schematic diagram illustrating an apparatus for generating an LFP battery model according to an embodiment of the present disclosure.

[0085] refer to Figure 7 The apparatus 100 for generating an LFP battery model according to embodiments of the present disclosure may include a lithium state recording unit 110 and a battery model generation unit 120. In an embodiment, the apparatus 100 for generating an LFP battery model according to embodiments of the present disclosure may be included in a battery management system (BMS) to generate a battery model of the LFP battery 1.

[0086] The lithium state recording unit 110 records the state of lithium in the positive electrode active material of the LFP battery 1 during charging or discharging of the LFP battery 1.

[0087] The battery model generation unit 120 generates a battery model of the LFP battery 1 based on the recorded state of lithium in the positive electrode active material. In an embodiment, the battery model generation unit 120 generates the battery model by modeling the LFP battery using multiple resistors and capacitors that reflect the state of lithium in the positive electrode active material.

[0088] In the following description, with reference to the accompanying drawings, an example of a specific method by which the lithium state recording unit 110 records the state of lithium in the positive electrode active material of the LFP battery 1, and the battery model generation unit 120 generates a battery model of the LFP battery 1 based on the recorded state of lithium in the positive electrode active material will be described.

[0089] Figure 8 This is a diagram illustrating a method for recording the state of lithium in the positive electrode active material of an LFP battery using a lithium state recording unit of an apparatus for generating an LFP battery model according to embodiments of the present disclosure.

[0090] refer to Figure 8 The figure shows the positive electrode active material of an LFP battery. The left side of the figure shows the positive electrode active material in the case of charging from a fully discharged state (i.e., 0% SOC value) to a 50% SOC value, and the right side of the figure shows the positive electrode active material in the case of discharging from a fully charged state (i.e., 100% SOC value) to a 50% SOC value.

[0091] As charging or discharging proceeds, the positive electrode active material repeatedly undergoes LFP and FP states, which can be represented by the following chemical formula.

[0092] [Chemical Formula 1]

[0093]

[0094] Through a chemical reaction as shown in the chemical formula, when... Figure 8 As shown on the left, during charging from a fully discharged state, Li+ ions flow from the outer portion of the positive electrode active material to the negative electrode. Here, the boundary between the outer FP and the inner LFP moves from the outer portion towards the center.

[0095] When Figure 8 As shown on the right, during discharge from a fully charged state, Li+ ions are pushed into the positive electrode from the outer portion of the active material. Here, the boundary between the outer LFP and the inner FP moves from the outer portion towards the center.

[0096] The state of lithium in such a positive electrode active material, i.e., the change in lithium distribution, can be represented by a one-dimensional bar graph from the periphery to the center of the positive electrode active material. For example, observe in Figure 8 The bar chart below represents... Figure 8When the right side is discharged from a fully charged state, and lithium is introduced from the outer part, the boundary between the outer LFP and the inner FP moves from the outer part to the center, and the side on the left side near the outer part becomes a rich phase with a large amount of lithium, while the side on the right side near the inner part becomes a poor phase with almost no lithium.

[0097] Here, "lithium distributed in the outer part" means that when modeling the positive electrode active material particles, lithium ions accumulate from the surface of the particles, forming a layer close to the particle surface. Due to the effect of this layer, lithium near the particle surface easily flows out during charging, while during discharging, it is difficult for the particles to easily flow in due to the presence of lithium near the particle surface.

[0098] Figure 9 This is an example of a lithium state recording unit recording the state of lithium in the positive electrode active material of an LFP battery in an apparatus for generating an LFP battery model according to an embodiment of the present disclosure.

[0099] refer to Figure 9 An example of a bar graph is shown, wherein the lithium state recording unit of the apparatus for generating an LFP battery model according to embodiments of the present disclosure uses Figure 8 The method records the state of lithium in the positive electrode active material of LFP batteries.

[0100] As above Figure 8 As described, during charging from a fully discharged state, when Li+ ions flow from the outer portion of the positive electrode active material to the negative electrode, the boundary between the outer FP and the inner LFP moves from the outer portion towards the center. Conversely, during discharging from a fully charged state, when Li+ ions are pushed into the positive electrode from the outer portion of the positive electrode active material, the boundary between the outer LFP and the inner FP moves from the outer portion towards the center.

[0101] The charge and discharge process is recorded using the battery's State of Charge (SOC) value. Here, the starting point of lithium ions can be represented as P_S, and the ending point as P_E. Internal layers can be formed based on this charge and discharge history, and to represent this layer information, P_S and P_E can be used as follows: Figure 9 The multiple arrangements shown.

[0102] Since the rich (β) phase and the poor (α) phase coexist in the positive electrode active material, the internal state is simulated only in the voltage-flat region (approximately 10% to 90% of the SOC value). However, for convenience, the simulation is also performed in other regions, and when applied to the model, the corresponding algorithm can reflect only the voltage-flat region in the positive electrode active material.

[0103] Figure 10 This is a diagram illustrating an example of the state of lithium in the positive electrode active material of an LFP battery recorded by a lithium state recording unit in an apparatus for generating an LFP battery model according to embodiments of the present disclosure, during charging of the LFP battery.

[0104] refer to Figure 10 This illustrates the state of lithium in the positive electrode active material of an LFP battery when it is being charged. When an LFP battery is charged, Li+ ions flow out through the outer portion of the positive electrode active material to the negative electrode, and therefore, the boundary between the outer FP and the inner LFP shifts from the outer portion towards the center.

[0105] exist Figure 10 In (a), as shown on the left, after being charged from 30% SOC to 40% SOC, the outer part is in a depleted phase, and since the Li+ ions located on the inside need to flow out through the depleted phase when charged to 100% SOC, the internal resistance is high.

[0106] exist Figure 10 In (c), as shown on the right, after discharging from 100% SOC to 40% SOC, the rich phase remains on the peripheral portion, and since Li+ ions can immediately flow out from the peripheral portion when charged to 50% SOC, the internal resistance is low.

[0107] exist Figure 10 In (b), as shown in the middle, after discharging from 50% SOC to 40% SOC, the rich phase remains on the outer portion. However, compared to case (c), there is less rich phase. Therefore, when charging to 50% SOC, the resistance gradually increases until all Li+ ions flow out from the outermost portion of the rich phase. Here, the internal resistance is related to the thickness of the outermost portion of the rich phase.

[0108] Figure 11 This is a diagram illustrating an example of the state of lithium in the positive electrode active material of an LFP battery recorded by a lithium state recording unit in an apparatus for generating an LFP battery model according to embodiments of the present disclosure, during the discharge of the LFP battery.

[0109] refer to Figure 11 This illustrates the state of lithium in the positive electrode active material of an LFP battery during discharge. When an LFP battery discharges, Li+ ions flow in from the negative electrode through the peripheral portion of the positive electrode active material, and thus, the boundary between the outer LFP and the inner LFP shifts towards the center.

[0110] exist Figure 11In (a), as shown on the left, after discharging from 60% SOC to 50% SOC, the peripheral portion is in a rich phase, and since the Li+ ions in the peripheral portion need to flow in through the rich phase when discharging to 0% SOC, the internal resistance is high.

[0111] exist Figure 11 In (c), as shown on the right, after charging from 0% SOC to 50% SOC, there is a depleted phase in the peripheral portion. Therefore, since Li+ ions can immediately flow in from the peripheral portion and settle immediately when discharged to 40% SOC, the internal resistance is low.

[0112] exist Figure 11 In (b), as shown in the middle, after charging from 40% SOC to 50% SOC, the depleted phase remains on the outermost portion. However, compared to case (c), there is less depleted phase. Therefore, when discharging to 40% SOC, the resistance gradually increases until Li+ ions fully occupy the outermost portion of the depleted phase. Here, the internal resistance is related to the thickness of the outermost portion of the depleted phase.

[0113] As described herein, the lithium state recording unit 110 of the apparatus 100 for generating an LFP battery model according to embodiments of this disclosure can be used Figures 8 to 11 The method was used to record the state of lithium in the positive electrode active material of LFP battery 1.

[0114] Figure 12 This is a diagram illustrating an example of a battery model generated by a battery model generation unit of an apparatus for generating an LFP battery model according to an embodiment of the present disclosure.

[0115] refer to Figure 12 According to embodiments of the present disclosure, the battery model generation unit 110 of the apparatus 100 for generating LFP battery models can include a first resistor (R_) in the equivalent circuit model (ECM). a ) and the second resistor (R_ b The battery model of the LFP battery is generated in the form of (Rp). In other words, in the battery model generated using the existing ECM method, the parallel resistor (Rp) is used. p ) and parallel capacitors (C P ) is retained, and the series resistance (R) s ) can be replaced by the first resistor (R_a) and the second resistor (R_b).

[0116] Here, the first resistance (R_a) represents the resistance component generated when viewed from the lithium surface away from the first lithium-ion layer, and the second resistance (R_b) refers to the resistance component generated as the thickness of the first lithium-ion layer on the surface changes.

[0117] Here, the resistance values ​​of the first resistor (R_a) and the second resistor (R_b) calculated by the battery model generation unit 110 may vary depending on charging or discharging, and the method for calculating the resistance values ​​of the first resistor (R_a) and the second resistor (R_b) will be described below.

[0118] Figure 13 and Figure 14 This is a diagram illustrating an example of a battery model generation unit of an apparatus for generating an LFP battery model according to an embodiment of the present disclosure, which generates a battery model based on the state of lithium in the positive electrode active material of the LFP battery recorded by a lithium state recording unit during charging of the LFP battery.

[0119] refer to Figure 13 and Figure 14 The battery model generation unit 110 can generate a battery model of an LFP battery by dividing the state of lithium into a first case and a second case. In the first case, when the LFP battery 1 is charged, lithium is not distributed on the outer part of the positive electrode active material of the LFP battery 1. In the second case, when the LFP battery 1 is charged, lithium is distributed on the outer part of the positive electrode active material of the LFP battery 1.

[0120] The first scenario is that lithium flows out due to the previous charging, leaving no lithium on the periphery of the positive electrode active material. The second scenario is that lithium flows in due to the previous discharging, accumulating on the periphery of the positive electrode active material. This lithium distribution is maintained regardless of whether there is a resting period between the previous and current states.

[0121] like Figure 13 As shown, in the first case, the internal resistance is high because when there is no lithium on the periphery of the positive electrode active material, during charging from 40% SOC to 50% SOC, the internal lithium ions need to flow out through the depleted phase. Here, as... Figure 14 As shown, the upper part of the graph for the first case can be considered as the contribution of the first resistor (R_a). In such a first case, the first resistor (R_a) can be a voltage drop resistor considering the voltage difference between the voltage of the LFP battery 1 measured according to at least one of SOC, charge and discharge rate (c-rate) and temperature, and the open circuit voltage (OCV) according to at least one of SOC and temperature, and the second resistor (R_b) can be 0.

[0122] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the LFP battery 1 measured according to at least one of SOC, charge and discharge rate and temperature is V_measurement(soc, c-rate, temp), the OCV according to at least one of SOC and temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rate is I_c-rate, and the first resistor is R_a, the first resistor (R_a) can be calculated by the following equation.

[0123] Equation 1

[0124]

[0125] like Figure 13 As shown, in the second case, when lithium accumulates on the outer portion of the positive electrode active material, charging begins from a 40% SOC value and proceeds through 45% to 50% SOC value. Lithium ions in the outer portion can immediately flow out, and the internal resistance gradually increases until all lithium ions flow out from the outermost portion of the enriched phase. Here, as... Figure 14 As shown, the upper part of the graph for the second case can be considered as the contribution of the second resistance (R_b). In this second case, the first resistance (R_a) can be 0, and the second resistance (R_b) can be a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the LFP battery in the voltage drop resistance, which varies depending on the SOC.

[0126] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the nearest lithium distribution start point to the periphery in the positive electrode active material of the LFP battery 1 according to the SOC is K_a(soc), the nearest lithium distribution end point to the periphery in the positive electrode active material of the LFP battery 1 at the start of charging after the discharge state or the resting state after discharge is K_b_captured, and the second resistor is R_b, the second resistor (R_b) can be calculated by the following equation.

[0127] Equation 2

[0128]

[0129] Figure 15 and Figure 16This is a diagram illustrating an example of a battery model generation unit of an apparatus for generating an LFP battery model according to embodiments of the present disclosure, which generates a battery model based on the state of lithium in the positive electrode active material of the LFP battery recorded by a lithium state recording unit during the discharge of the LFP battery.

[0130] refer to Figure 15 and Figure 16 The battery model generation unit 110 can generate a battery model of an LFP battery by dividing the state of lithium into a third case and a fourth case. In the third case, when the LFP battery 1 is discharged, lithium is not distributed on the outer part of the positive electrode active material of the LFP battery 1. In the fourth case, when the LFP battery 1 is discharged, lithium is distributed on the outer part of the positive electrode active material of the LFP battery 1.

[0131] The third scenario is that lithium flows out due to the previous charging, leaving no lithium on the outer part of the positive electrode active material. The fourth scenario is that lithium flows in due to the previous discharging, accumulating on the outer part of the positive electrode active material. This lithium distribution is maintained regardless of whether there is a resting period between the previous and current states.

[0132] like Figure 15 As shown, the internal resistance is high in the fourth case because when lithium accumulates on the periphery of the positive electrode active material, during discharge from a SOC value of 40% through 35% to 30%, lithium ions on the periphery need to pass through the enriched phase to flow in. Here, as... Figure 16 As shown, the lower part of the graph for the fourth case can be considered as the contribution of the second resistor (R_b). In this fourth case, the first resistor (R_a) can be 0, and the second resistor (R_b) can be a voltage drop resistor considering the voltage difference between the voltage of the LFP battery 1 measured according to at least one of SOC, charge and discharge rate, and temperature, and the OCV measured according to at least one of SOC and temperature.

[0133] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the LFP battery 1 measured according to at least one of SOC, charge and discharge rate and temperature is V_measurement(soc, c-rate, temp), the OCV according to at least one of SOC and temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rate is I_c-rate, and the second resistor is R_b, the second resistor (R_b) can be calculated by the following equation.

[0134] Equation 3

[0135]

[0136] like Figure 15 As shown, in the third case, when there is no lithium on the outer portion of the positive electrode active material, during discharge from 50% SOC through 45% to 40% SOC, lithium ions in the outer portion can flow in and immediately settle, thus the resistance gradually increases until lithium ions fully occupy the outermost portion of the depleted phase. Here, as... Figure 16 As shown, the lower part of the graph for the third case can be considered as the contribution of the first resistance (R_a). In this third case, the first resistance (R_a) can be a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the LFP battery in the voltage drop resistance, which varies depending on the SOC, and the second resistance (R_b) can be 0.

[0137] In an embodiment, when the voltage drop resistor is R_vdrop(soc, c-rate, temp), the nearest lithium distribution endpoint to the periphery in the positive electrode active material of the LFP battery 1 according to the SOC is K_b(soc), the nearest lithium distribution starting point to the periphery in the positive electrode active material of the LFP battery 1 at the moment of discharge start after the charging state or the resting state after charging is Ka_a_captured, and the first resistor is R_a, the first resistor (R_a) can be calculated by the following equation.

[0138] Equation 4

[0139]

[0140] According to embodiments of this disclosure, by recording the state of lithium in the positive electrode active material of the LFP battery 1 during charging or discharging, and generating a battery model of the LFP battery 1 based on the recorded state of lithium in the positive electrode active material, it is possible to record how the state of lithium in the positive electrode active material changes depending on the history of previous charging and discharging paths, and it is possible to define how the internal resistance changes depending on the current internal state of the positive electrode reflecting the history of previous charging and discharging paths, and these can ultimately be applied to the battery model.

[0141] According to embodiments of this disclosure, by generating a battery model that reflects the internal state of the positive electrode active material (which varies depending on the history of previous charging and discharging paths), accuracy can be increased by reducing errors in the battery model, and thus, errors in the state of charge (SOC) and state of health (SOH) of the battery calculated from the BMS can be reduced.

[0142] Figure 17This is a flowchart describing a method for generating an LFP battery model according to embodiments of the present disclosure.

[0143] refer to Figure 17 The method for generating an LFP battery model according to embodiments of the present disclosure may include steps S210 to S220.

[0144] Step S210 is a step of recording the state of lithium (Li) in the positive electrode active material of a lithium iron phosphate (LiFePO4, LFP) battery according to the charging or discharging of the LFP battery in the lithium state recording unit. In an embodiment, step S210 may include a step of recording the distribution state of lithium in the positive electrode active material of the LFP battery from the peripheral portion to the center, which varies depending on the charging or discharging of the LFP battery.

[0145] Step S220 is a battery model generation step in the battery model generation unit that generates a battery model of the LFP battery based on the recorded state of lithium in the positive electrode active material. In an embodiment, step S220 may include a step of generating a battery model by modeling the LFP battery using multiple resistors and capacitors that reflect the state of lithium in the positive electrode active material.

[0146] In an embodiment, step S220 may include generating a battery model of the LFP battery in the form of a first resistor and a second resistor in an equivalent circuit model (ECM).

[0147] In an embodiment, step S220 may further include generating a battery model of the LFP battery by dividing the state of lithium into a first case and a second case, wherein in the first case, when the LFP battery is charged, lithium is not distributed on the periphery of the positive electrode active material of the LFP battery, and in the second case, when the LFP battery is charged, lithium is distributed on the periphery of the positive electrode active material of the LFP battery.

[0148] In another embodiment, step S220 may further include generating a battery model of the LFP battery by dividing the state of lithium into a third case and a fourth case, wherein in the third case, lithium is not distributed on the periphery of the positive electrode active material of the LFP battery when the LFP battery is discharged, and in the fourth case, lithium is distributed on the periphery of the positive electrode active material of the LFP battery when the LFP battery is discharged.

[0149] A method for generating an LFP battery model according to embodiments of the present disclosure described herein has been described with reference to the flowcharts presented in the accompanying drawings. For simplicity, the method has been shown and described with a series of blocks; however, the present disclosure is not limited to the order of the blocks, and some blocks may be performed in a different order than that shown and described herein or simultaneously with other blocks, and various other branches, flow paths, and block orders may be implemented to achieve the same or similar results. Furthermore, not all blocks shown may be necessary to illustrate the method described herein.

[0150] At the same time, in reference Figure 17 In the description, according to embodiments of this disclosure, each step can be further divided into additional steps or combined into fewer steps. Additionally, some steps may be omitted as needed, and the order of the steps can also be varied. Furthermore, even for other descriptions that do not include steps, refer to... Figures 1 to 16 The provided description can be used as a reference. Figure 17 The description provided. Additionally, see references. Figure 17 The provided description can be used as a reference. Figures 1 to 16 The description provided.

[0151] The following describes substances that can be used in secondary batteries according to embodiments of the present disclosure.

[0152] Compounds capable of reversibly inserting and deintercalating lithium (e.g., lithiation intercalation compounds) can be used as positive electrode active materials. Specifically, composite oxides selected from metals, one or more selected from cobalt, manganese, nickel and combinations thereof, and lithium can be used as positive electrode active materials.

[0153] The composite oxide can be a lithium transition metal composite oxide. Detailed examples of composite oxides may include lithium nickel-based oxides, lithium cobalt-based oxides, lithium manganese-based oxides, lithium iron phosphate-based compounds, cobalt-free nickel manganese-based oxides, or combinations thereof.

[0154] For example, a compound represented by one of the following chemical formulas can be used: Li a A1- b X b O2- c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn2- b X b O4- c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni1-b-c Co b X c O2- α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b-c Mn b X c O2- α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90≤a≤1.8, 0≤g≤0.5); Li （3-f） Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0155] In the chemical formula, A can be Ni, Co, Mn, or a combination thereof. X can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D can be O, F, S, P, or a combination thereof. G can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof. L 1 It can be Mn, Al, or a combination thereof.

[0156] The positive electrode of a lithium secondary battery may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material, and may also include a binder and / or a conductive material.

[0157] The content of the positive electrode active material can be from 90 wt.% to 99.5 wt.% relative to 100 wt.% of the positive electrode active material layer. The content of the binder and conductive material can be from 0.5 wt.% to 5 wt.% relative to 100 wt.% of the positive electrode active material layer.

[0158] Al can be used as a current collector, but this disclosure is not limited thereto.

[0159] The negative electrode active material may include materials capable of reversibly inserting / de-intercalating with respect to lithium ions, lithium metal, lithium metal alloys, materials capable of being doped and de-doped with respect to lithium, or transition metal oxides.

[0160] Materials capable of reversibly intercalating / deintercalating relative to lithium ions can include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Examples of crystalline carbon can include graphite, such as natural or synthetic graphite. Examples of amorphous carbon can include soft or hard carbon, mesophase pitch carbides, and calcined coke.

[0161] Si-based or Sn-based negative electrode active materials can be used as materials capable of being doped and dedoped relative to lithium. Si-based negative electrode active materials can be silicon, silicon-carbon composites, or SiO₂. x (0 < x < 2), Si-based alloys or combinations thereof.

[0162] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to an embodiment, the silicon-carbon composite can include silicon particles and can be in the form of amorphous carbon having been coated on the surface of the silicon particles.

[0163] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles, and an amorphous carbon coating layer disposed on the surface of the core.

[0164] The negative electrode of a lithium secondary battery may include a current collector and a negative electrode active material layer disposed on the current collector. The negative electrode active material layer may include a negative electrode active material, and may also include a binder and / or a conductive material.

[0165] For example, the negative electrode active material layer may include 90 wt.% to 99 wt.% of negative electrode active material, 0.5 wt.% to 5 wt.% of binder and 0 wt.% to 5 wt.% of conductive material.

[0166] Non-aqueous binders, aqueous binders, dry binders, or combinations thereof can be used as binders. If an aqueous binder is used as the binder for the negative electrode, the binder for the negative electrode may further include cellulose-based compounds capable of imparting viscosity.

[0167] A current collector selected from nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer bases coated with conductive metal, and combinations thereof, which can be used as a negative electrode.

[0168] Electrolytes used in lithium secondary batteries may include non-aqueous organic solvents and lithium salts.

[0169] Non-aqueous organic solvents can act as a medium, allowing ions involved in the electrochemical reactions of the battery to move through it.

[0170] Non-aqueous organic solvents can be carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents, aprotic solvents, or combinations thereof. Carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvents or aprotic solvents can be used alone, or two or more of them can be mixed and used as non-aqueous organic solvents.

[0171] In addition, if carbonate-based solvents are used, cyclic carbonates and chain carbonates can be mixed.

[0172] Depending on the type of lithium-ion secondary battery, a separator may be present between the positive and negative electrodes. Polyethylene, polypropylene, and polyvinylidene fluoride, or multilayers having two or more of these layers, can be used as separators.

[0173] The diaphragm may include a porous substrate and a coating layer disposed on one or both sides of the porous substrate, comprising organic, inorganic or combinations thereof.

[0174] Organic materials may include polyvinylidene fluoride polymers or (meth)acrylic acid polymers.

[0175] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof, but this disclosure is not limited thereto.

[0176] Organic and inorganic substances can be in the form in which organic and inorganic substances are mixed in a coating layer or in the form in which a coating layer including organic substances and a coating layer including inorganic substances are stacked.

[0177] Although this disclosure has been described herein with reference to limited embodiments and accompanying drawings, this disclosure is not limited to these embodiments. Those skilled in the art to which this disclosure pertains can modify and alter this disclosure within the spirit of the disclosure and the equivalents of the appended claims.

Claims

1. An apparatus for generating a lithium iron phosphate (LFP) battery model, the apparatus comprising: A lithium state recording unit records the state of lithium Li in the positive electrode active material of the lithium iron phosphate LFP battery during charging or discharging. and The battery model generation unit generates a battery model of the lithium iron phosphate (LFP) battery based on the recorded state of lithium in the positive electrode active material. The battery model generation unit generates the battery model by modeling the lithium iron phosphate (LFP) battery using multiple resistors and capacitors that reflect the state of lithium in the positive electrode active material.

2. The apparatus according to claim 1, wherein, The lithium state recording unit records the distribution of lithium from the periphery to the center in the positive electrode active material of the lithium iron phosphate LFP battery, and the distribution changes depending on the charging or discharging of the lithium iron phosphate LFP battery.

3. The apparatus according to claim 2, wherein, The battery model generation unit generates the battery model of the lithium iron phosphate LFP battery in the form of a first resistor and a second resistor in the equivalent circuit model ECM.

4. The apparatus according to claim 3, wherein, The battery model generation unit generates the battery model of the lithium iron phosphate (LFP) battery by dividing the state of lithium into a first case and a second case. In the first case, when the LFP battery is charged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery. In the second case, when the LFP battery is charged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

5. The apparatus according to claim 4, wherein, In the first case generated in the battery model generation unit, the first resistor is a voltage drop resistor that takes into account a voltage difference between the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), charge and discharge rate (c-rate), and temperature, and the open-circuit voltage (OCV) measured according to at least one of the SOC and the temperature, and the second resistor is 0.

6. The apparatus according to claim 5, wherein, When the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), the charge and discharge rates, and the temperature is V_measurement(soc, c-rate, temp), the open-circuit voltage OCV according to at least one of the SOC and the temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rates is I_c-rate, and the first resistor is R_a, the first resistor R_a is calculated by the following equation: 。 7. The apparatus according to claim 6, wherein, In the second case generated in the battery model generation unit, the first resistance is 0, and the second resistance has a resistance value obtained by reflecting the distribution state of lithium in the positive electrode active material of the lithium iron phosphate LFP battery in the voltage drop resistor, the distribution state varying depending on the state of charge (SOC).

8. The apparatus according to claim 7, wherein, When the voltage drop resistor is R_vdrop(soc, c-rate, temp), the starting point of the lithium distribution closest to the peripheral portion in the positive electrode active material of the lithium iron phosphate LFP battery according to the state of charge (SOC) is K_a(soc), the ending point of the lithium distribution closest to the peripheral portion in the positive electrode active material of the lithium iron phosphate LFP battery at the start of charging after discharge or post-discharge rest is K_b_captured, and the second resistor is R_b, the second resistor R_b is calculated by the following equation: 。 9. The apparatus according to claim 3, wherein, The battery model generation unit generates the battery model of the lithium iron phosphate (LFP) battery by dividing the state of lithium into a third case and a fourth case. In the third case, when the LFP battery is discharged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery. In the fourth case, when the LFP battery is discharged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

10. The apparatus according to claim 9, wherein, In the fourth case generated in the battery model generation unit, the first resistor is 0, and the second resistor is a voltage drop resistor that takes into account a voltage difference between the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), charge and discharge rate (c-rate), and temperature, and the open-circuit voltage (OCV) measured according to at least one of the SOC and the temperature.

11. The apparatus according to claim 10, wherein, When the voltage drop resistor is R_vdrop(soc, c-rate, temp), the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), the charge and discharge rates, and the temperature is V_measurement(soc, c-rate, temp), the open-circuit voltage OCV according to at least one of the SOC and the temperature is V_ocv_ch(soc, temp), the current flowing through the voltage drop resistor according to the charge and discharge rates is I_c-rate, and the second resistor is R_b, the second resistor R_b is calculated by the following equation: 。 12. The apparatus according to claim 11, wherein, In the third case generated in the battery model generation unit, the first resistor has a resistance value obtained by reflecting the distribution state of lithium in the positive electrode active material of the lithium iron phosphate LFP battery in the voltage drop resistor, the distribution state varying depending on the state of charge (SOC), and the second resistor is 0.

13. The apparatus according to claim 12, wherein, When the voltage drop resistor is R_vdrop(soc, c-rate, temp), the nearest lithium distribution endpoint to the peripheral portion in the positive electrode active material of the lithium iron phosphate LFP battery according to the state of charge (SOC) is K_b(soc), the nearest lithium distribution starting point to the peripheral portion in the positive electrode active material of the lithium iron phosphate LFP battery at the start of discharge after charging or resting state after charging is Ka_a_captured, and the first resistor is R_a, the first resistor R_a is calculated by the following equation: 。 14. A method for generating a lithium iron phosphate (LFP) battery model, the method comprising: The lithium state recording step records the state of lithium Li in the positive electrode active material of the lithium iron phosphate LFP battery according to the charging or discharging of the lithium iron phosphate LFP battery in the lithium state recording unit. and The battery model generation step involves generating a battery model of the lithium iron phosphate (LFP) battery in the battery model generation unit based on the recorded state of lithium in the positive electrode active material. The battery model generation step includes generating the battery model by modeling the lithium iron phosphate LFP battery using multiple resistors and capacitors that reflect the state of lithium in the positive electrode active material.

15. The method according to claim 14, wherein, The lithium state recording step includes recording the distribution of lithium from the periphery to the center in the positive electrode active material of the lithium iron phosphate LFP battery, the distribution of which varies depending on the charging or discharging of the lithium iron phosphate LFP battery.

16. The method according to claim 15, wherein, The battery model generation step includes generating the battery model of the lithium iron phosphate LFP battery in the form of a first resistor and a second resistor in the equivalent circuit model ECM.

17. The method according to claim 16, wherein, The battery model generation step further includes generating the battery model of the lithium iron phosphate (LFP) battery by dividing the state of lithium into a first case and a second case. In the first case, when the LFP battery is charged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery. In the second case, when the LFP battery is charged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

18. The method according to claim 17, wherein, In the first case generated in the battery model generation step, the first resistor is a voltage drop resistor considering a voltage difference between the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), charge and discharge rate (c-rate), and temperature, and the open-circuit voltage (OCV) measured according to at least one of the SOC and the temperature, and the second resistor is 0. In the second case generated in the battery model generation step, the first resistor is 0, and the second resistor has a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the lithium iron phosphate LFP battery in the voltage drop resistor, the distribution varying depending on the state of charge (SOC).

19. The method of claim 16, wherein, The battery model generation step further includes generating the battery model of the lithium iron phosphate (LFP) battery by dividing the state of lithium into a third case and a fourth case, wherein in the third case, when the LFP battery is discharged, lithium is not distributed in the peripheral portion of the positive electrode active material of the LFP battery, and in the fourth case, when the LFP battery is discharged, lithium is distributed in the peripheral portion of the positive electrode active material of the LFP battery.

20. The method according to claim 19, wherein, In the fourth case generated in the battery model generation step, the first resistance is 0, and the second resistance is a voltage drop resistor considering a voltage difference between the voltage of the lithium iron phosphate LFP battery measured according to at least one of the state of charge (SOC), charge and discharge rate (c-rate), and temperature, and the open-circuit voltage (OCV) measured according to at least one of the SOC and the temperature. In the third case generated in the battery model generation step, the first resistance has a resistance value obtained by reflecting the distribution of lithium in the positive electrode active material of the lithium iron phosphate LFP battery in the voltage drop resistor, the distribution varying depending on the SOC, and the second resistance is 0.

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