Method for generating recipe for multi step constant current (MSCC) charging and method for manufacturing secondary battery using same

Abstract

According to exemplary embodiments, a method for generating a recipe for multi step current charging (MSCC) charging is provided. The method comprises the steps of: charging a modeling cell to collect charging data on the modeling cell; deriving a current-capacitance model on the basis of the charging data; and generating a recipe for MSCC charging on the basis of the current-capacitance model.

Description

Method for generating a recipe for MSCC (MULTI-STEP CONSTANT CURRENT) charging and a method for manufacturing a secondary battery using the same

[0001] The present invention relates to a method for generating a recipe for Multi-Step Constant Current (MSCC) charging and a method for manufacturing a secondary battery using the same.

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0139120 dated October 14, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Unlike primary batteries, secondary batteries can be charged and discharged multiple times. Secondary batteries are widely used as energy sources for various wireless devices such as handsets, laptops, and cordless vacuum cleaners. Recently, as the manufacturing cost per unit capacity of secondary batteries has decreased dramatically due to improved energy density and economies of scale, and as the driving range of BEVs (battery electric vehicles) has increased to a level equivalent to that of fuel vehicles, the primary use of secondary batteries is shifting from mobile devices to mobility.

[0004] The manufacturing of a secondary battery includes an electrode process including mixing, coating, roll pressing, slitting, and notching processes, an assembly process for embedding the electrode assembly into a case, and an activation process for electrically activating and stabilizing the battery cell.

[0005] The problem that the technical concept of the present invention aims to solve is to provide a method for generating a Multi-Step Constant Current (MSCC) charging recipe that can improve the throughput of a method for manufacturing a secondary battery.

[0006] According to exemplary embodiments of the present invention for solving the above-described problem, a method for generating a recipe for Multi-Step Current Charging (MSCC) is provided. The method comprises the steps of: charging a modeling cell to collect charging data of the modeling cell; deriving a current-capacitance model based on the charging data; and generating a recipe for MSCC charging based on the current-capacitance model.

[0007] The above recipe includes the number of steps of the MSCC filling.

[0008] The above recipe includes the magnitude of the current in each of the steps of the MSCC charging.

[0009] The above current-capacitance model represents the capacitance of the equivalent capacitor of the modeling cell according to the magnitude of the current applied to the modeling cell.

[0010] The step of generating the above recipe is further based on the following Equation 1.

[0011] [Equation 1]

[0012]

[0013] Here, t n is the duration of the nth step of the MSCC charging above, and I n is the magnitude of the current of the n-th step of the above MSCC charging, and V MCn is the magnitude of the voltage applied to the modeling cell at the completion of the nth step of the MSCC charging, and V Rn is the magnitude of the voltage applied to the equivalent resistance of the modeling cell in the nth step of the MSCC charging, and V n is the magnitude of the voltage applied to the equivalent capacitor of the modeling cell at the start of the nth step of the MSCC charging, and C b (I n ) is the magnitude of the current of the nth step of the MSCC charge In When, it is the capacitance of the equivalent capacitor of the modeling cell determined based on the above current-capacitance model, and and n is an integer greater than or equal to 1.

[0014] [Equation 2]

[0015]

[0016] Here, R B is the resistance value (Resistance) of the equivalent resistance of the above modeling cell.

[0017] V n ... satisfies the following Equation 3.

[0018] [Equation 3]

[0019]

[0020] Here, V MCn-1 is the voltage applied to the modeling cell at the completion of the n-1th step of the MSCC charging, and I n-1 is the magnitude of the current of the n-1th step of the MSCC charge.

[0021] The above recipe is determined by SLSQP (Sequential Least Squares Programming).

[0022] The above SLSQP includes a condition for minimizing the time of the MSCC filling according to the above recipe.

[0023] The magnitude of each of the MSCC charging steps of the above recipe is greater than the magnitude of the current of the subsequent MSCC charging step of the above recipe.

[0024] The method comprises the steps of: generating a recipe for MSCC charging; and charging a plurality of battery cells based on the recipe, wherein the plurality of battery cells are connected in series.

[0025] The above recipe is generated based on a current-capacitance model, and the above current-capacitance model represents the capacitance of the equivalent capacitor of the modeling cell according to the current applied to the modeling cell.

[0026] The above modeling cell is manufactured through the same process as the above plurality of battery cells.

[0027] The above recipe includes the number of steps of the MSCC filling.

[0028] The above recipe includes the magnitude of the current in each of the steps of the MSCC charge.

[0029] According to exemplary embodiments of the present invention, a Multi-Step Constant Current (MSCC) charging recipe provides a current magnitude for each step that minimizes the charging speed according to the number of steps of the MSCC charging. Accordingly, by determining the number of steps of the MSCC charging recipe and the current magnitude for each step, the throughput of secondary battery manufacturing can be improved.

[0030] The effects obtainable from the exemplary embodiments of the present invention are not limited to those mentioned above, and other unmentioned effects can be clearly derived and understood by those skilled in the art to which the exemplary embodiments of the present disclosure belong from the following description. That is, unintended effects resulting from the implementation of the exemplary embodiments of the present disclosure can also be derived by those skilled in the art from the exemplary embodiments of the present disclosure.

[0031] FIG. 1 is a flowchart illustrating a method for generating a recipe for a Multi Step Constant Current (MSCC) charge according to exemplary embodiments.

[0032] Figure 2 is a circuit diagram showing the charging of a modeling cell.

[0033] Figure 3 shows the current and voltage over time of MSCC charging.

[0034] Figure 4 is a capacitance-voltage graph of MSCC charging.

[0035] Figure 5 is a capacitance-current graph of MSCC charging.

[0036] FIG. 6 is a table showing the magnitude of the current in each step according to the number of steps of the recipe for MSCC charging according to exemplary embodiments.

[0037] FIG. 7 is a flowchart illustrating a method for manufacturing a secondary battery in exemplary embodiments.

[0038] FIG. 8 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0039] Figure 9 shows the time index generated from a simulation to generate a recipe for MSCC filling according to the number of steps of MSCC filling, and the measured time required for MSCC filling.

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings. Instead, based on the principle that the inventor can appropriately define the concepts of terms to best describe his invention, they should be interpreted in a meaning and concept consistent with the technical spirit of the present invention.

[0041] Therefore, the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention; thus, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0042] In addition, in describing the present invention, if it is determined that a detailed description of related known components or functions may obscure the essence of the invention, such detailed description is omitted.

[0043] Since embodiments of the present invention are provided to more fully explain the invention to those skilled in the art, the shapes and sizes of the components in the drawings may be exaggerated, omitted, or schematically depicted for clearer explanation. Accordingly, the size or proportion of each component does not entirely reflect the actual size or proportion.

[0044]

[0045] (1st embodiment)

[0046] FIG. 1 is a flowchart illustrating a method for generating a recipe for a Multi Step Constant Current (MSCC) charge according to exemplary embodiments.

[0047] Figure 2 is a circuit diagram showing the charging of a modeling cell (MC).

[0048] Figure 3 shows the current and voltage over time of MSCC charging.

[0049] Figure 4 is a capacitance-voltage graph of MSCC charging.

[0050] Figure 5 is a capacitance-current graph of MSCC charging.

[0051] FIG. 6 is a table showing the magnitude of the current in each step according to the number of steps of the recipe for MSCC charging according to exemplary embodiments.

[0052] Referring to FIGS. 1 to 3, in P110, the modeling cell (MC) can be charged to collect charging data of the modeling cell (MC). Unlike in FIG. 8, where multiple battery cells (BC1, BC2, ..., BCN) are charged at once, the modeling cell (MC) can be charged as a single unit. That is, the modeling cell (MC) can be charged while loaded into a charging facility that includes a variable current source configured to supply current (IS), and charging data including electrical parameters of the modeling cell (MC) (e.g., voltage, current, and capacity) can be collected while the modeling cell (MC) is being charged.

[0053] The modeling cell (MC) may include a cell case and an electrode assembly housed in the cell case. The modeling cell (MC) may further include an electrolyte injected into the cell case, but is not limited thereto. The modeling cell (MC) may include, for example, a solid electrolyte integrated into the electrode assembly.

[0054] According to exemplary embodiments, the electrode assembly may include a stacked structure of a plurality of anodes, a plurality of cathodes, and a plurality of separators isolating the plurality of anodes and the plurality of cathodes. According to other exemplary embodiments, the electrode assembly may include a wound structure of anodes, cathodes, and separators. The cell case may include any one of a rectangular metal can, a cylindrical metal can, and a pouch case comprising a laminated metal (e.g., aluminum) layer.

[0055] Each of the plurality of positives may include a positive current collector and a positive active material. The thickness of the positive current collector may be in the range from about 3 μm to about 500 μm. The positive current collector may not cause chemical changes in the secondary battery finally manufactured and may have high conductivity. The positive current collector may include, for example, any one of stainless steel, nickel, titanium, calcined carbon, and aluminum. The positive current collector may also include stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The surface of the positive current collector may include a micro-irregular structure to increase the adhesion of the active material. The shape of the positive current collector may include any one of a film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0056] The positive electrode active material is a material capable of causing an electrochemical reaction. The positive electrode active material may be a lithium transition metal oxide. The positive electrode active material may be, for example, a layered compound such as lithium cobalt oxide (LiCoO2) and lithium nickel oxide (LiNiO2) substituted with one or more transition metals; lithium manganese oxide substituted with one or more transition metals; or a material with the chemical formula LiNi 1-y M y Lithium nickel-based oxide represented by O2 (where M is any one of Co, Mn, Al, Cu, Fe, Mg, B, Cr, Zn, and Ga, and 0.01≤y≤0.7); Li 1+z Ni 1 / 3 Co 1 / 3 Mn 1 / 3 O2, Li 1+zN i 0.4 Mn 0.4 Co 0.2 Li like O2 1+z Ni b Mn c Co 1-(b+c+d) M d O (2-e) A eA lithium nickel cobalt manganese composite oxide represented by (where -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d<1, M is any one of Al, Mg, Cr, Ti, Si and Y, and A is any one of F, P and Cl); and chemical formula Li 1+x M 1-y M' y PO 4-z X z It may include any one of the olivine-based lithium metal phosphates represented by (wherein M is a transition metal, more specifically one of Fe, Mn, Co and Ni, M' is one of Al, Mg and Ti, X is one of F, S and N, -0.5≤x≤+0.5, 0≤y≤0.5, and 0≤z≤0.1).

[0057] Each of the plurality of negative electrodes (EN) may include a negative current collector and a negative active material. The thickness of the negative current collector may be in the range of about 3 μm to about 500 μm. The negative current collector may not cause chemical changes in the secondary battery finally manufactured and may have high conductivity. The negative current collector may include any one of copper, stainless steel, aluminum, nickel, titanium, calcined carbon, and aluminum-cadmium alloy. The negative current collector may also include stainless steel surface-treated with carbon, nickel, titanium, silver, etc. The surface of the negative current collector may include a micro-irregular structure to increase the adhesion of the active material. The shape of the negative current collector may include any one of a film, sheet, foil, net, porous material, foam, and nonwoven fabric.

[0058] The negative electrode active material may include carbon, for example, non-graphitizable carbon, graphite-based carbon, etc. The negative electrode active material is, for example, Li x Fe2O3(0≤x≤1), LixWO2(0≤x≤1), Sn x Me1-x Me y O z (wherein Me is any one of Mn, Fe, Pb, and Ge, and Me' is any one of Al, B, P, Si, Group 1, Group 2, and Group 3 elements of the periodic table, and halogens; 0 <x≤1 이고; 1≤y≤3 이며; 1≤z≤8) 등의 금속 복합 산화물을 포함할 수 있다. 음극 활물질은, 예컨대, 리튬 금속; 리튬 합금; 규소계 합금; 및 주석계 합금 중 어느 하나를 포함할 수 있다. 음극 활물질은, 예컨대, SnO, SnO2, PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4및 Bi2O5등의 금속 산화물을 포함할 수 있다. 음극 활물질은, 예컨대, 폴리아세틸렌 등의 도전성 고분자; Li-Co-Ni 계 재료 등을 포함할 수도 있다.

[0059] The electrolyte may be any one of a non-aqueous electrolyte, an aqueous electrolyte, an ionic electrolyte, and a gel electrolyte. The electrolyte may also be a solid electrolyte. The non-aqueous electrolyte may include organic solvents such as ethylene carbonate and dimethyl carbonate, and lithium salts such as LiPF6 and LiBF4 dissolved in organic solvents. The non-aqueous electrolyte may also include ethylene carbonate dissolved in tetraethylammonium salts. The aqueous electrolyte may include sodium sulfate solution, sulfuric acid solution, hydrochloric acid solution, or sodium hydroxide solution. The ionic electrolyte is an ionic compound that is in a liquid state at room temperature, such as ethylmethylimidazolidium bis(trifluoromethylsulfonyl)amide, and has high thermal stability. The gel electrolyte may be provided by using a liquid electrolyte such as polyacrylonitrile and PVA. The solid electrolyte may include a polymer material doped with a lithium salt (e.g., polyethylene oxide (PEO)) and a ceramic electrolyte composed of ceramic materials such as NASICON and LLZO.

[0060]

[0061] The modeling cell (MC) can be modeled with an equivalent resistance (RB) and an equivalent capacitor (CB). The modeling cell (MC) can be charged in the manner of MSCC charging, but is not limited thereto. Generally, the magnitude of the current (IS) in the preceding step of MSCC charging can be greater than the magnitude of the current (IS) in the subsequent step. For example, as illustrated in the graph of FIG. 3, the magnitude of the current (IS) in the first step can be greater than the magnitude of the current (IS) in the second step, the magnitude of the current (IS) in the second step can be greater than the magnitude of the current (IS) in the third step, the magnitude of the current (IS) in the third step can be greater than the magnitude of the current (IS) in the fourth step, and the magnitude of the current (IS) in the fourth step can be greater than the magnitude of the current (IS) in the fifth step.

[0062] The voltage (VMC) applied to the modeling cell (MC) is the sum of the voltage (VRB) applied to the equivalent resistor (RB) and the voltage (VCB) applied to the equivalent capacitor (CB). Accordingly, the voltage (VCB) applied to the equivalent capacitor (CB) is equal to the difference between the voltage (VMC) applied to the modeling cell (MC) and the voltage (VRB) applied to the equivalent resistor (RB).

[0063] In each step of the MSCC charging recipe, the modeling cell (MC) is charged to the charging voltage (VC), and the voltage (VRB) applied to the equivalent resistance (RB) is proportional to the current. When transitioning from a preceding step to a subsequent step, if the magnitude of the current (IS) decreases, the voltage (VRB) applied to the equivalent resistance (RB) decreases, and thus the voltage (VMC) applied across the modeling cell (MC) also decreases. As the equivalent capacitor (CB) is charged by the current (IS), the voltage (VMC) applied to the modeling cell (MC) rises again to the charging voltage (VC).

[0064] Charging the modeling cell (MC) involves storing the target capacity in the equivalent capacitor (CB) of each modeling cell (MC), which is equivalent to charging the equivalent capacitor (CB) with current (IS) so that the voltage (VCB) applied to the equivalent capacitor (CB) becomes the target voltage.

[0065] In the final step of the MSCC, if each modeling cell (MC) is charged to the charging voltage (VC) with a sufficiently low current (IS), the equivalent capacitor (CB) of each modeling cell (MC) can be charged to the target capacity.

[0066] Next, referring to FIGS. 1, FIGS. 2, FIGS. 4, and FIGS. 5, a current-capacitance model can be derived based on charging data in P120.

[0067] As illustrated in FIG. 4, it was confirmed that the slope of the capacitance-voltage curve is at least partially constant in the first to eighth steps of MSCC charging. Since the slope of the capacitance-voltage curve is equal to the capacitance of the equivalent capacitor (CB) of each modeling cell (MC), sufficient consistency with respect to the capacitance of the equivalent capacitor (CB) of the modeling cell (MC) can be ensured even when the capacitance of the equivalent capacitor (CB) of the modeling cell (MC) is modeled with the magnitude of the current (IS). A person skilled in the art will be able to easily arrive at an embodiment in which, based on the charging data of the modeling cell (MC), the capacitance of the equivalent capacitor (CB) of the modeling cell (MC) is modeled with a number of variables including the magnitude of the voltage (VMC) applied to the modeling cell (MC) and the magnitude of the current (IS), based on what is described herein.

[0068] According to exemplary embodiments, a current-capacitance model representing the capacitance of the equivalent capacitor (CB) of the modeling cell (MC) according to the current (IS) can be derived from the charging data of the modeling cell (MC). The derivation of the current-capacitance model may be based on data modeling regarding the capacitance of the equivalent capacitor (CB) of each modeling cell (MC) in the charging data and the magnitude of the current (IS) applied to the modeling cell (MC). Such data modeling may utilize methodologies of regression analysis such as linear regression, polynomial regression, logistic regression, and multiple regression, but is not limited thereto. FIG. 5 is a graph representing the current-capacitance model derived from P120.

[0069] At this time, in order to derive the current-capacitance model, collecting charging data of the modeling cell (MC) in P110 can be performed repeatedly for multiple different modeling cells (MC), and accordingly, deriving the current-capacitance model in P120 can be based on charging data collected from multiple modeling cells (MC).

[0070]

[0071] Next, referring to FIGS. 1 and FIGS. 5, in P130, a recipe for MSCC charging can be generated based on a current-capacitance model. Generating the recipe for MSCC charging may include determining the number of steps of the MSCC charging recipe and the magnitude of the current for each step, based on the following Equation 1, to satisfy the minimum charging time condition. Accordingly, the recipe for MSCC charging includes the number of steps of MSCC charging and the magnitude of the current for each step of MSCC charging.

[0072]

[0073] Here, t n is the duration of the nth step of MSCC charging. I nε is the magnitude of the current (IS) of the nth step of the MSCC charge. V MCn is the magnitude of the voltage (VMC) applied to the modeling cell (MC) at the completion of the n-th step of MSCC charging. V Rn ε is the magnitude of the voltage (VRB) applied to the equivalent resistance (RB) of the modeling cell (MC) at the n-th step of MSCC charging. V n is the magnitude of the Open Circuit Voltage of the modeling cell (MC) at the start of the nth step of MSCC charging. C b (I n ) is the magnitude of the current (IS) of the n-th step of MSCC charging I n It is the capacitance of the equivalent capacitor (CB) determined based on the current-capacitance model when. n is an integer greater than or equal to 1.

[0074] V Rn It satisfies the following mathematical formula 2.

[0075]

[0076] Here, R B is the resistance value (Resistance) of the equivalent resistance (RB) of the modeling cell (MC).

[0077] V n is equal to the magnitude of the voltage (VCB) applied to the equivalent capacitor (CB) of the modeling cell (MC) at the start of the n-th step of MSCC charging. V n It satisfies the following mathematical formula 3.

[0078]

[0079] Here, V MCn-1 is the voltage applied to the modeling cell (MC) at the completion of the n-1th step of MSCC charging, and I n-1 is the magnitude of the current (IS) at the (n-1)th step of the MSCC charge. When n=1, I0 is generally 0, and V MC0 It can have an initial voltage that is 0 or non-0.

[0080] The recipe for MSCC packing can be determined, for example, by an optimization methodology. One example of such a methodology is Sequential Least Squares Programming (SLSQP). SLSQP is an optimization algorithm used to solve nonlinear programming problems with equality and inequality constraints. SLSQP works by linearizing the objective function and constraints in each iteration and then solving the linearized problem. This method uses a quasi-Newtonian approach that improves convergence speed by approximating the Lagrangian's Hessian. SLSQP is available through the optimize module of Python's SciPy library, as shown in the code below.

[0081]

[0082] res = minimize(func, x0, method='SLSQP', bounds=bnds, constraints=cons)

[0083] print('Optimal solution:', res.x)

[0084] print('Minimum value:', res.fun)

[0085] Optimal solution: [61.08 50.79856993 42.87768134 36.58998626 31.40140849 27.00740182 23.22887954 19.9528082 17.10314354 14.62432914 12.4728853 10.61208643 9.00915843 7.634]

[0086] Minimum value: 356.1335555839794

[0087]

[0088] Func is the charging time to be minimized, x0 contains the condition regarding the magnitude of the current (IS) in the first step, Bnds is the limit condition regarding the range of the current, and CONSTRAINTS are the boundary conditions for the simulation. The boundary condition states that in each step of MSCC charging, the magnitude of the current (IS) in the subsequent step is smaller than the magnitude of the current (IS) in the preceding step.

[0089] The Optimal solution represents the magnitude of the current for each of the 14 steps when the MSCC charging includes 14 steps. The Minimum value is an index of an arbitrary unit representing the charging time. The index is not the actual measured time, but has a value proportional to the time required according to the simulation.

[0090] FIG. 6 shows the current of each step of the MSCC charging recipe satisfying the minimum charging time condition for 10 cases in which the MSCC charging includes 5 to 14 steps. The unit of current is mA.

[0091]

[0092] (2nd Example)

[0093] FIG. 7 is a flowchart illustrating a method for manufacturing a secondary battery according to exemplary embodiments.

[0094] FIG. 8 is a flowchart for explaining a secondary battery manufacturing facility (100) according to exemplary embodiments.

[0095] Figure 9 shows the actual time required for MSCC filling of a recipe that includes 5 to 14 steps and satisfies the minimum filling time condition of MSCC.

[0096] Referring to FIGS. 7 and FIGS. 8, a recipe for MSCC filling can be generated at P100. The recipe for MSCC filling can be provided in substantially the same manner as described with reference to P110 to P130 of FIG. 1.

[0097] Next, referring to FIGS. 7 and 9, a plurality of battery cells (BC1, BC2,..., BCN) can be charged based on the MSCC charging recipe. The plurality of battery cells (BC1, BC2,..., BCN) can be charged by a secondary battery manufacturing facility (100).

[0098] Multiple battery cells (BC1, BC2,..., BCN) can be manufactured through substantially the same process as multiple modeling cells (MC, see FIG. 2). Multiple battery cells (BC1, BC2,..., BCN) can have specifications similar to those of multiple modeling cells (MC, see FIG. 2). Accordingly, a current-capacitance model derived from a current-capacitance model generated from charging data for multiple modeling cells (MC, see FIG. 2) can also be valid for multiple battery cells (BC1, BC2,..., BCN), and a recipe for MSCC charging generated based on the current-capacitance model of multiple modeling cells (MC, see FIG. 2) can satisfy minimum charging time conditions for multiple battery cells (BC1, BC2,..., BCN).

[0099] In FIG. 2, unlike the case where charging data of a modeling cell (MC) that is charged individually is collected, a plurality of battery cells (BC1, BC2,..., BCN) can be charged at least partially simultaneously. A secondary battery manufacturing facility (100) may include a variable current source (110) for charging a plurality of battery cells (BC1, BC2,..., BCN) at least partially simultaneously, and a plurality of switching elements (SW11, SW12, SW21, SW22,..., SWN1, SWN2) configured to connect a plurality of battery cells (BC1, BC2,..., BCN) in series and provide an electrical path that bypasses some of the plurality of battery cells (BC1, BC2,..., BCN).

[0100] For example, the switching element (SW11) can provide an electrical path for charging the battery cell (BC1) or block the electrical path for charging the battery cell (BC1). The switching element (SW12) can provide a path for bypassing the battery cell (BC1) if, at a specific step of the MSCC charging recipe, the battery cell (BC1) is fully charged before some of the battery cells (BC2, ..., BCN).

[0101] More specifically, when a specific step of the MSCC charging recipe begins, the switching elements (SW11, SW21,..., SWN1) may be in the ON state and the switching elements (SW12, SW22,..., SWN2) may be in the OFF state. Accordingly, a plurality of battery cells (BC1, BC2,..., BCN) connected in series can be charged by the variable current source (110).

[0102] Due to production tolerances (i.e., allowable error) and tolerances of the charging environment, multiple battery cells (BC1, BC2,..., BCN) do not all have the same characteristics. Accordingly, some of the multiple battery cells (BC1, BC2,..., BCN) are charged first, and others of the multiple battery cells (BC1, BC2,..., BCN) are charged later.

[0103] For example, when battery cell (BC1) is charged first, the switching element (SW11) is switched from an ON state to an OFF state and the switching element (SW12) is switched from an OFF state to an ON state, thereby terminating the charging of battery cell (BC1) and providing a bypass path including the switching element (SW12). Accordingly, each of the battery cells (BC2, ..., BCN) can be charged until it reaches a charging voltage at a specific step of MSCC charging. The above-described operation of the plurality of switching operations (SW11, SW12, SW21, SW22, ..., SWN1, SWN2) can be repeated in a similar manner until all of the plurality of battery cells (BC1, BC2, ..., BCN) are charged. After all of the plurality of battery cells (BC1, BC2, ..., BCN) have reached a charging voltage at a specific step of MSCC charging, the current for the next step of MSCC charging can be applied.

[0104] Due to various delays including such switching operations, additional delay time is required when the number of steps in MSCC charging increases. Referring to FIG. 9, it was confirmed that as the number of steps increases, the time index due to the charging itself decreases. At this time, due to the accumulation of additional delay time caused by the increase in the number of steps, it was confirmed that the time required for MSCC charging is shortest when the MSCC charging includes 7 to 8 steps.

[0105] According to exemplary embodiments, a recipe for MSCC charging with a minimum charging time condition can be generated, which allows for MSCC-based series charging as described below. Generally, since the voltage of each battery cell is at the level of several volts, there is significant energy loss due to voltage reduction of the commercial voltage during MSCV (Multi Stage Constant Voltage) charging. According to exemplary embodiments, by connecting multiple battery cells in series to perform MSCC charging, voltage transformation is unnecessary, thereby preventing energy loss caused by voltage transformation. Furthermore, by charging multiple battery cells connected in series based on an MSCC charging recipe that satisfies the minimum charging time condition, the throughput of secondary battery manufacturing can be improved.

[0106] Furthermore, the recipe for the MSCC step can be determined based on additional limiting conditions, such as the current size of the first step according to the quality of the CEI (Cathode Electrolyte Interphase) layer and SEI (Solid Electrolyte Interphase) layer, and the charging time at a specific voltage level for energy expression of a specific active material.

[0107] The present invention has been described in more detail above through drawings and embodiments. However, the configurations described in the drawings or embodiments described in this specification are merely one embodiment of the present invention and do not represent all technical concepts of the present invention; therefore, it should be understood that various equivalents and modifications that can replace them may exist at the time of filing this application.

Claims

1. A step of charging the modeling cell to collect charging data of the modeling cell; A step of deriving a current-capacitance model based on the above charging data; and A method for generating a recipe for MSCC charging, comprising the step of generating a recipe for MSCC (Multi Step Current Charging) charging based on the above current-capacitance model.

2. In Paragraph 1, A method for generating a recipe for MSCC filling characterized by including the number of steps of the MSCC filling above.

3. In Paragraph 2, A method for generating a recipe for MSCC charging, characterized in that the above recipe includes the magnitude of the current of each of the steps of the MSCC charging.

4. In Paragraph 1, A method for generating a recipe for MSCC charging, characterized in that the above current-capacitance model represents the capacitance of the equivalent capacitor of the modeling cell according to the magnitude of the current applied to the modeling cell.

5. In Paragraph 1, The step of generating the above recipe is further based on the following Equation 1, and [Equation 1] Here, t n is the duration of the nth step of the MSCC charging above, and I n is the magnitude of the current of the n-th step of the above MSCC charging, and V MCn is the magnitude of the voltage applied to the modeling cell at the completion of the nth step of the MSCC charging, and V Rn is the magnitude of the voltage applied to the equivalent resistance of the modeling cell in the nth step of the MSCC charging, and V n is the magnitude of the voltage applied to the equivalent capacitor of the modeling cell at the start of the nth step of the MSCC charging, and C b (I n ) is the magnitude of the current of the nth step of the MSCC charge I n A method for generating a recipe for MSCC charging, characterized in that the capacitance of the equivalent capacitor of the modeling cell is determined based on the current-capacitance model when, and n is an integer greater than or equal to 1.

6. In Paragraph 5, V Rn ... satisfies the following Equation 2, and [Equation 2] Here, R B A method for generating a recipe for MSCC charging, characterized in that is the resistance value of the equivalent resistance of the above-mentioned modeling cell.

7. In Paragraph 6, V n ... satisfies the following Equation 3, and [Equation 3] Here, V MCn-1 is the voltage applied to the modeling cell at the completion of the n-1th step of the MSCC charging, and I n-1 A method for generating a recipe for MSCC charging characterized in that the magnitude of the current of the n-1th step of the MSCC charging is 8. In Paragraph 7, A method for generating a recipe for MSCC filling, characterized in that the above recipe is determined by SLSQP (Sequential Least Squares Programming).

9. In Paragraph 8, A method for generating a recipe for MSCC filling, characterized in that the above SLSQP includes a condition for minimizing the time of MSCC filling according to the above recipe.

10. In Paragraph 8, A method for generating an MSCC charging recipe characterized in that the magnitude of each of the MSCC charging steps of the above recipe is greater than the magnitude of the current of the subsequent MSCC charging step of the above recipe.

11. Step for generating a recipe for MSCC filling; and The method includes the step of charging a plurality of battery cells based on the above recipe, A method for manufacturing a secondary battery characterized in that the plurality of battery cells are connected in series.

12. In Paragraph 11, The above recipe is generated based on a current-capacitance model, and A method for manufacturing a secondary battery characterized in that the above current-capacitance model represents the capacitance of the equivalent capacitor of the modeling cell according to the current applied to the modeling cell.

13. In Paragraph 12, A method for manufacturing a secondary battery characterized in that the above-mentioned modeling cell is manufactured through the same process as the above-mentioned plurality of battery cells.

14. In Paragraph 11, A method for manufacturing a secondary battery characterized by the above recipe including the number of steps of the MSCC charge.

15. In Paragraph 12, A method for manufacturing a secondary battery characterized by the above recipe including the magnitude of the current in each of the steps of the MSCC charge.

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