Deterioration estimation device, deterioration estimation method, and deterioration estimation program

Abstract

To provide a deterioration estimation device, a deterioration estimation method, and a deterioration estimation program capable of reducing a processing load on estimation of deterioration of a secondary battery without limiting timing for estimating the deterioration of the secondary battery.SOLUTION: A deterioration estimation device 10 includes: a side reaction current calculation unit 131 for calculating a side reaction current generated in a negative electrode of a secondary battery by using temperature of the secondary battery; and a deterioration index calculation unit for calculating a deterioration index of the secondary battery based on the side reaction current calculated by the side reaction current calculation unit 131.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a deterioration estimation device, a deterioration estimation method, and a deterioration estimation program for estimating the deterioration of a secondary battery. [Background technology]

[0002] Currently, secondary batteries such as lithium-ion batteries and nickel-metal hydride batteries are used in vehicles that use electric power as a driving force, such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles. Various techniques have been proposed to estimate the deterioration of such secondary batteries.

[0003] As an example of a technology for estimating the deterioration of a secondary battery, Patent Document 1 discloses a deterioration estimation device that changes the capacity retention rates of the positive and negative electrodes so that the estimated value of the open circuit voltage curve matches the actual measured value, and estimates the deterioration of the secondary battery by performing convergence calculations. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-190979 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the degradation estimation device disclosed in Patent Document 1 has the problem that the timing for estimating the degradation of a secondary battery is limited because it needs to acquire actual measured values of the open-circuit voltage curve when the secondary battery is not in use. Also, this degradation estimation device has the problem that the processing load for estimating the degradation of a secondary battery is large because it estimates the degradation of a secondary battery using convergence calculation.

[0006] The present invention solves these problems and aims to provide a deterioration estimation device, a deterioration estimation method, and a deterioration estimation program that do not restrict the timing of estimating the deterioration of a secondary battery and that can reduce the processing load associated with estimating the deterioration of a secondary battery. [Means for solving the problem]

[0007] A deterioration estimation device for estimating deterioration of a secondary battery according to one aspect of the present invention includes: a side reaction current calculation unit that calculates a side reaction current occurring at a negative electrode of the secondary battery using the temperature of the secondary battery; The secondary battery includes a deterioration index calculation unit that calculates a deterioration index of the secondary battery based on the side reaction current calculated by the side reaction current calculation unit.

[0008] The deterioration estimation device also an ion concentration calculation unit that calculates the current ion concentration on the solid phase surface of the negative electrode using the side reaction current; a decrease amount calculation unit that calculates an amount of decrease in ion concentration on the solid phase surface of the negative electrode using the past ion concentration on the solid phase surface of the negative electrode and the current ion concentration on the solid phase surface of the negative electrode calculated by the ion concentration calculation unit; The battery may further include a capacity calculation unit that calculates the capacity of the secondary battery as a deterioration index using the amount of decrease in ion concentration calculated by the decrease amount calculation unit.

[0009] Furthermore, the deterioration estimation device a coating thickness calculation unit that calculates the thickness of a coating formed on a solid electrolyte interface on the negative electrode using the side reaction current; The device may further include a film resistance calculation unit that calculates the resistance of the film at the solid electrolyte interface using the film thickness as a deterioration index.

[0010] Furthermore, the side reaction current can be calculated based on a parameter determined by the temperature of the secondary battery, the time of the aging treatment performed on the secondary battery, the coating thickness calculated by the coating thickness calculation unit, and the initial value of the coating thickness at the solid electrolyte interface.

[0011] A deterioration estimation method for estimating deterioration of a secondary battery according to one aspect of the present invention includes: A side reaction current occurring at the negative electrode of the secondary battery is calculated using the temperature of the secondary battery; A deterioration index of the secondary battery is calculated based on the calculated side reaction current.

[0012] The degradation estimation method is as follows: The side reaction current is used to calculate the current ion concentration on the solid surface of the negative electrode. Calculating the amount of decrease in ion concentration on the solid phase surface of the negative electrode using the past ion concentration on the solid phase surface of the negative electrode and the calculated current ion concentration on the solid phase surface of the negative electrode; The capacity of the secondary battery can be calculated using the calculated amount of decrease in ion concentration as a deterioration index.

[0013] Furthermore, the degradation estimation method is The thickness of the coating at the solid electrolyte interface formed on the negative electrode is calculated using the side reaction current. The coating thickness can be used to calculate the resistance at the coating at the solid electrolyte interface as a degradation indicator.

[0014] A deterioration estimation program for estimating deterioration of a secondary battery according to one aspect of the present invention includes: Calculating a side reaction current occurring at the negative electrode of the secondary battery using the temperature of the secondary battery; and a step of calculating a deterioration index of the secondary battery based on the calculated side reaction current.

[0015] In addition, the deterioration estimation program Calculating the current ion concentration on the solid surface of the negative electrode using the side reaction current; Calculating the amount of decrease in the ion concentration on the solid phase surface of the negative electrode using the past ion concentration on the solid phase surface of the negative electrode and the calculated current ion concentration on the solid phase surface of the negative electrode; The computer may be caused to execute a step of calculating the capacity of the secondary battery as a deterioration index using the calculated amount of decrease in ion concentration.

[0016] Furthermore, the deterioration estimation program Calculating the thickness of the coating at the solid electrolyte interface formed on the negative electrode using the side reaction current; and calculating the resistance of the coating at the solid electrolyte interface using the coating thickness as a degradation indicator. [Effects of the Invention]

[0017] The present invention makes it possible to provide a deterioration estimation device, a deterioration estimation method, and a deterioration estimation program that do not restrict the timing for estimating the deterioration of a secondary battery and that can reduce the processing load associated with estimating the deterioration of a secondary battery. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram showing the configuration of a deterioration estimation device according to an embodiment of the present invention; [Figure 2] FIG. 10 is a diagram showing the shift of corresponding points between the positive electrode and the negative electrode caused by a change in ion concentration on the solid-phase surface of the negative electrode due to the generation of a side reaction current, and a concept for correcting the shift of these corresponding points. [Figure 3] FIG. 1 is a diagram illustrating a parameter Y in Equation 1. [Figure 4] FIG. 1 is a diagram illustrating a parameter Z in Equation 1. [Figure 5] FIG. 11 is a diagram illustrating a parameter YW in Equation 11. [Figure 6] FIG. 11 is a diagram illustrating a parameter ZW in Equation 11. [Figure 7] 3 is a flowchart illustrating an example of processing executed by a deterioration estimation device according to an embodiment of the present invention. [Figure 8] FIG. 10 is a diagram showing an example of a change over time in the increment of DC internal resistance of a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will be described below with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a deterioration estimation device 10 according to an embodiment of the present invention. The deterioration estimation device 10 is a device that estimates the deterioration of a secondary battery installed in a vehicle. A specific example of the deterioration estimation device 10 is an ECU (Electronic Control Unit) installed in a vehicle. The deterioration estimation device corresponds to a computer.

[0020] The deterioration estimation device 10 includes a communication interface (I / F) 11, a storage device 12, and a calculation device 13. The communication I / F 11 is an interface for transmitting and receiving signals between the deterioration estimation device 10 and a secondary battery and other devices installed in the vehicle.

[0021] The storage device 12 is a storage device that stores the deterioration estimation program executed by the arithmetic device 13 and various information processed by the arithmetic device 13 .

[0022] The arithmetic device 13 is an arithmetic device such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). The arithmetic device corresponds to a computer. The arithmetic device 13 executes a deterioration estimation program stored in the storage device 12, thereby performing a deterioration estimation method defined by the deterioration estimation program.

[0023] The degradation estimation program is a program that calculates a side reaction current occurring at the negative electrode of a secondary battery using the temperature of the secondary battery whose degradation is to be estimated, and calculates a degradation index of the secondary battery based on the calculated side reaction current. The degradation estimation program includes a temperature acquisition unit 130, a side reaction current calculation unit 131, an ion concentration calculation unit 132, a decrease amount calculation unit 133, a capacity calculation unit 134, a coating thickness calculation unit 135, and a coating resistance calculation unit 136. Note that these programs may be executed by an integrated circuit such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The integrated circuit corresponds to a computer.

[0024] The temperature acquisition unit 130 is a program that acquires the temperature (K) of the secondary battery. The temperature acquisition unit 130 can acquire the temperature of the secondary battery from a temperature sensor (not shown) that measures the temperature of the secondary battery via the communication I / F 11. The temperature acquisition unit 130 acquires the temperature of the secondary battery at a predetermined time interval. Hereinafter, the time interval at which the temperature acquisition unit 130 acquires the temperature of the secondary battery will be referred to as the sampling time. Furthermore, the number of times that the temperature acquisition unit 130 acquires the temperature of the secondary battery will be referred to as the sampling count.

[0025] The side reaction current calculation unit 131 is a program that calculates the side reaction current occurring at the negative electrode of the secondary battery using the temperature of the secondary battery acquired by the temperature acquisition unit 130. The side reaction current calculation unit 131 calculates the side reaction current I SEI Calculate.

number

number

[0026] X shown in Equation 1 is a parameter defined in Equation 3.

number

[0027] Y in Equation 1 is a parameter determined by the temperature T [K] of the secondary battery, and is defined by Equation 4.

number

[0028] Z in Equation 1 is a parameter determined by the temperature T [K] of the secondary battery, and is defined by Equation 5.

number

[0029] Here, the method for deriving Y and Z will be explained. The change over time in the side reaction current at each temperature (for example, 60°C, 70°C, 75°C, etc.) is power-approximated, and a power approximation formula for the side reaction current is derived for each temperature. The period for approximating the change over time in the side reaction current can be the aging time required for the secondary battery and the storage period. Next, as shown in Figure 3, the coefficients of the power approximation formula for the side reaction current at each temperature are linearly approximated using an Arrhenius plot. The slope of the obtained approximate linear formula is A in Equation 4. coeff Also, the intercept of this approximate straight line is B in Equation 4. coeff is equivalent to

[0030] As shown in Figure 4, the multipliers of the power approximation formula of the side reaction current at each temperature are plotted on a graph with the horizontal axis representing temperature (°C), and a linear approximation is performed. The slope of the obtained linear approximation formula is A in Equation 5. multi Also, the intercept of this approximate straight line is B in Equation 5. multi is equivalent to

[0031] As shown in Equation 1, the side reaction current calculation unit 131 calculates the side reaction current by using parameters Y and Z determined by the temperature of the secondary battery, the time t0 of the aging treatment performed on the secondary battery, and the past coating thickness δ calculated by the coating thickness calculation unit 135 (to be described later). SEI and the initial thickness of the coating at the solid electrolyte interface δ SEI,INI For example, the side reaction current (I SEI When calculating (2), the side reaction current calculation unit 131 calculates the coating thickness (δ SEI (1)) to calculate the side reaction current (I SEI (2)) is calculated.

[0032] The ion concentration calculation unit 132 is a program that calculates the current ion concentration on the solid-phase surface of the negative electrode using the side reaction current of the negative electrode calculated by the side reaction current calculation unit 131. The ion concentration calculation unit 132 calculates the current ion concentration on the solid-phase surface of the negative electrode based on Equation 6 and Equation 7.

number

number

number

[0033] The decrease amount calculation unit 133 is a program that calculates the amount of decrease in ion concentration on the solid phase surface of the negative electrode, using the past ion concentration on the solid phase surface of the negative electrode and the current ion concentration on the solid phase surface of the negative electrode calculated by the ion concentration calculation unit 132. Specifically, the decrease amount calculation unit 133 can calculate the amount of decrease in ion concentration by subtracting the current ion concentration from the past ion concentration on the solid phase surface of the negative electrode.

[0034] When the decrease in ion concentration is calculated for the first time, the previous ion concentration on the solid-phase surface of the negative electrode is the initial value of the ion concentration on the solid-phase surface of the negative electrode. When the decrease in ion concentration is calculated for the second time or later, the previous ion concentration on the solid-phase surface of the negative electrode calculated by the ion concentration calculation unit 132 is used as the previous ion concentration on the solid-phase surface of the negative electrode.

[0035] Generally, when a solid electrolyte interfacial film grows on an electrode, a side reaction current flows. In this embodiment, it is assumed that the growth of the solid electrolyte interfacial film occurs mainly at the negative electrode, and the side reaction current flows mainly at the negative electrode. In this case, since discharge appears to occur only at the negative electrode, the ion concentration at the solid-phase surface of the negative electrode decreases.

[0036] Fig. 2 shows the shift in the corresponding points of the positive and negative electrodes caused by the change in ion concentration on the solid-phase surface of the negative electrode due to the generation of a side reaction current, and the concept of correcting this shift in the corresponding points. Fig. 2 shows the OCPs (Open Circuit Potentials) of the positive and negative electrodes before and after the generation of a side reaction current at the negative electrode, and the OCV (Open Circuit Voltage) corresponding to the difference between these OCPs.

[0037] FIG. 2 shows, as an example, corresponding points of the positive and negative electrodes that indicate the ion concentrations and potentials of the positive and negative electrodes when the SOC (State of Charge) is 50%. Before the side reaction current occurs, the ion concentrations indicated by the corresponding points of the positive and negative electrodes are the same. When a side reaction current occurs at the negative electrode, the ion concentration at the solid-phase surface of the negative electrode decreases due to discharge, causing the corresponding points of the positive and negative electrodes to shift. The decrease amount calculation unit 133 calculates the decrease amount of the ion concentration at the solid-phase surface of the negative electrode.

[0038] The capacity calculation unit 134 is a program that calculates the capacity of the secondary battery using the amount of decrease in ion concentration on the solid-phase surface of the negative electrode calculated by the decrease amount calculation unit 133. The capacity calculation unit 134 corresponds to a deterioration index calculation unit.

[0039] Specifically, the capacity calculation unit 134 corrects the positive electrode OCP according to the amount of decrease in the ion concentration at the solid-phase surface of the negative electrode calculated by the decrease amount calculation unit 133. This correction corresponds to a shift of the positive electrode OCP curve shown in FIG. 2 to the left. Next, the capacity calculation unit 134 calculates the ion concentration [mol] corresponding to the potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 0% and the ion concentration [mol] corresponding to the potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 100%. In the example shown in FIG. 2, the potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 0% is 3.0 (V), and the potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 100% is 4.1 (V). Then, the capacity calculation unit 134 calculates the difference Li between these ion concentrations. amo The capacity of the secondary battery can be calculated by substituting the above into Equation 9.

number

[0040] In this way, the capacity calculation unit 134 can calculate the capacity of the secondary battery after the capacity has been reduced due to the occurrence of a side reaction current at the negative electrode. Note that the capacity calculation unit 134 may calculate the capacity of the secondary battery reduced due to the occurrence of a side reaction current at the negative electrode, i.e., the difference between the capacity before the occurrence of the side reaction current and the capacity after the occurrence of the side reaction current.

[0041] In the example shown in FIG. 2, the OCV curve is set so that the points at which the difference between the corrected positive electrode OCP curve and the negative electrode OCP curve is 3.0 (V) and 4.1 (V) are located at both ends of the corrected OCV curve. However, it should be noted that the corrected OCV curve is not limited to that shown in FIG. 2.

[0042] The coating thickness calculation unit 135 is a program that calculates the coating thickness of the solid electrolyte interface formed on the negative electrode using the negative electrode side reaction current calculated by the side reaction current calculation unit 131. The coating thickness calculation unit 135 calculates the coating thickness δ of the solid electrolyte interface of the negative electrode based on Equation 10 and Equation 11. SEI and coating thickness d W [cm]. Coating thickness δ SEI represents the film thickness based on the relationship between capacity decrease and side reaction current. W represents the resistance distance based on the relationship between the resistance increase and the side reaction current, that is, the length that contributes to the resistance in the coating. W corresponds to the second coating thickness.

number

number

number

[0043] Y W is a parameter determined by the temperature T [K] of the secondary battery, and is defined by Equation 13.

number

number

[0044] Here, A shown in Equation 13 coeff,w and Bcoeff,w and A shown in Equation 14 multi,w and B multi,w FIG. 8 is a diagram showing an example of the change over time in the increment of DC internal resistance (DCIR) of a secondary battery based on measurement data at each temperature over a predetermined period (e.g., storage period). In the example shown in FIG. 8, measurement data of the DC internal resistance of the secondary battery at 60°C, 70°C, 75°C, and 80°C is used. Measurement data at other temperatures can also be used. Using this measurement data, the increment of DC internal resistance from the initial value is calculated for each temperature. Then, the change over time in the increment of DC internal resistance at each temperature is approximated by a power law.

[0045] In addition, based on the following formula 15, the increment ΔR of the solid electrolyte interface film resistance SEI Calculate.

number

number

[0046] Therefore, Equation 15 is defined as Equation 17.

number

[0047] The increment ΔR of the solid electrolyte interfacial film resistance defined by Equation 17 SEI The gain W(k) at each temperature (60°C, 70°C, 75°C, 80°C, etc.) during the storage period of the secondary battery is calculated so that the increment of the DC internal resistance, which is power-approximated based on the measurement data, matches the increment of the DC internal resistance, which is power-approximated based on the measurement data. Next, the obtained gain W(k) at each temperature is power-approximated to derive a power approximation formula for the gain W(k) at each temperature. Then, the coefficients of the power approximation formula for the gain W(k) at each temperature are linearly approximated using an Arrhenius plot, as shown in FIG. 5. The slope of the obtained approximate linear formula is A in Equation 13. coeff,w Also, the intercept of this approximate straight line is B in Equation 13. coeff,w is equivalent to

[0048] Similarly, the multipliers of the power approximation formula of the gain W(k) for each temperature are plotted on a graph with the horizontal axis representing temperature (°C) as shown in Figure 6, and linear approximation is performed. The slope of the obtained approximate linear formula is A in Equation 14. multi,w Also, the intercept of this approximate straight line is B in Equation 14. multi,w is equivalent to

[0049] The coating thickness calculation unit 135 calculates the above A based on Equation 13. coeff,w and B coeff,w and the temperature T of the secondary battery, Y W Furthermore, the coating thickness calculation unit 135 calculates the above A based on Equation 14. multi,w and B multi,w and the temperature T of the secondary battery, Z W Next, the coating thickness calculation unit 135 calculates the above Y W and Z W Then, the coating thickness calculation unit 135 calculates the gain W(k) based on Equation 11 using the gain W(k). The coating thickness calculation unit 135 calculates the second coating thickness d W Calculate.

[0050] The coating resistance calculation unit 136 calculates the second coating thickness d of the solid electrolyte interface of the negative electrode calculated by the coating thickness calculation unit 135. W The film resistance calculation unit 136 corresponds to the deterioration index calculation unit. The film resistance calculation unit 136 calculates the solid electrolyte interface film resistance R based on Equation 16. SEI can be calculated.

[0051] Fig. 7 is a flowchart showing an example of processing executed by the deterioration estimation device 10. The deterioration estimation device 10 repeatedly executes the processing shown in Fig. 7 at predetermined sampling intervals.

[0052] In step S1, the temperature acquisition unit 130 acquires the temperature of the secondary battery. In step S2, the side reaction current calculation unit 131 calculates the side reaction current occurring at the negative electrode of the secondary battery using the temperature of the secondary battery.

[0053] In step S3, the ion concentration calculation unit 132 calculates the current ion concentration on the solid-phase surface of the negative electrode using the side reaction current of the negative electrode. In step S4, the decrease calculation unit 133 calculates the decrease in ion concentration on the solid-phase surface of the negative electrode using the past ion concentration on the solid-phase surface of the negative electrode and the current ion concentration on the solid-phase surface of the negative electrode calculated in step S3. In step S5, the capacity calculation unit 134 calculates the current capacity of the secondary battery using the decrease in ion concentration on the solid-phase surface of the negative electrode calculated in step S4.

[0054] In step S6, the coating thickness calculation unit 135 calculates the first coating thickness and the second coating thickness of the negative electrode. In step S7, the coating resistance calculation unit 136 calculates the solid electrolyte interface coating resistance using the second coating thickness of the negative electrode calculated in step S6.

[0055] In the above-described embodiment, the deterioration estimation device 10 calculates the side reaction current occurring at the negative electrode of the secondary battery using the temperature of the secondary battery. Then, the deterioration estimation device 10 calculates a deterioration index of the secondary battery based on the calculated side reaction current. In this embodiment, the only measurement value required to calculate the side reaction current is the temperature of the secondary battery, which can be obtained while the secondary battery is in use. Therefore, even when the secondary battery is in use, the deterioration estimation device 10 can calculate the deterioration index of the secondary battery based on the side reaction current calculated using the temperature of the secondary battery, and there is no restriction on the timing for estimating the deterioration of the secondary battery.

[0056] Furthermore, the deterioration estimation device 10 does not use convergence calculations to calculate the side reaction current and the deterioration index of the secondary battery, which reduces the processing load required to estimate the deterioration of the secondary battery compared to techniques that use convergence calculations to calculate the deterioration index.

[0057] In the above-described embodiment, the ion concentration calculation unit 132 calculates the current ion concentration on the solid-phase surface of the negative electrode using the side reaction current. Next, the decrease amount calculation unit 133 calculates the decrease amount of the ion concentration on the solid-phase surface of the negative electrode using the past ion concentration on the solid-phase surface of the negative electrode and the current ion concentration on the solid-phase surface of the negative electrode calculated by the ion concentration calculation unit 132. Then, the capacity calculation unit 134 calculates the capacity of the secondary battery using the decrease amount of the ion concentration calculated by the decrease amount calculation unit 133. This makes it possible to calculate the capacity of the secondary battery as a deterioration index of the secondary battery.

[0058] Furthermore, in the above-described embodiment, the coating thickness calculation unit 135 calculates the thickness of the coating at the solid electrolyte interface formed on the negative electrode using the side reaction current. Then, the coating resistance calculation unit 136 calculates the resistance of the coating at the solid electrolyte interface using the coating thickness. This makes it possible to calculate the resistance of the coating at the solid electrolyte interface as a deterioration index of the secondary battery.

[0059] In the above examples, the program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may also be transmitted on a transient computer-readable medium or communication medium. By way of example and not limitation, transient computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals. Computers include various devices such as PCs (personal computers), servers, CPUs, MPUs, FPGAs, ASICs, etc.

[0060] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention. [Explanation of symbols]

[0061] 10 Deterioration estimation device 11 Communication Interface 12 Storage device 13 Arithmetic unit 130 Temperature acquisition section 131 Side reaction current calculation unit 132 Ion concentration calculation unit 133 Decrease amount calculation section 134 Capacity calculation section 135 Film thickness calculation section 136 Film resistance calculation section

Claims

1. A deterioration estimation device for estimating deterioration of a secondary battery, comprising: a temperature acquisition unit that acquires a measured temperature of an outer surface of the secondary battery; a side reaction current calculation unit that calculates a side reaction current occurring at the negative electrode of the secondary battery using the acquired measured temperature; an ion concentration calculation unit that calculates a current ion concentration on the solid-phase surface of the negative electrode using the side reaction current; a decrease amount calculation unit that calculates an amount of decrease in ion concentration on the solid phase surface of the negative electrode using the current ion concentration on the solid phase surface of the negative electrode and a past ion concentration on the solid phase surface of the negative electrode that was calculated before the ion concentration calculation unit calculated the current ion concentration; a capacity calculation unit that calculates a capacity of the secondary battery using the amount of decrease in the ion concentration as a deterioration index of the secondary battery; Equipped with The side reaction current calculation unit calculates the side reaction current based on Equation 1, [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode, δ SEI (k-1) represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode calculated based on the measurement temperature previously obtained, δ SEI,INI represents a known initial value of the thickness of the coating at the solid electrolyte interface formed on the negative electrode, t 0 represents an aging treatment time indicating the storage period of the secondary battery, X is a parameter defined by Equation 3, Y is a parameter defined by Equation 4, and Z is a parameter defined by Equation 5, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density [kg / cm 3 ] of the solid electrolyte interface. [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, the ion concentration calculation unit calculates a current ion concentration on the solid-phase surface of the negative electrode based on Equation 6 and Equation 7, [Equation 6] [Equation 7] Here, c avg represents the average Li concentration [mol / cm 3 ] of the active material, R p represents the radius of the active material, c s represents the Li concentration on the surface of the active material, D s represents the diffusion coefficient of Li in the solid phase of the negative electrode, and j Li SEI represents the ion flux on the solid phase surface of the secondary battery, and is defined by Equation 8: [Equation 8] where I SEI represents the side reaction current, a s represents the specific surface area of the active material, F is Faraday's constant, L p represents the thickness of the positive electrode of the secondary battery, L n represents the thickness of the negative electrode, and A represents the area of the coated portion of the negative electrode. The capacitance calculation unit correcting a positive electrode OCP (Open Circuit Potential) in accordance with a decrease in ion concentration on the solid phase surface of the negative electrode; calculating a first ion concentration corresponding to a potential difference between a positive electrode OCP and a negative electrode OCP when an SOC (State of Charge) of the secondary battery is 0% and a second ion concentration corresponding to a potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 100%; Substituting the difference Li amo between the first ion concentration and the second ion concentration into Equation 9 to calculate the capacity of the secondary battery; [Equation 9] where F is the Faraday constant. Deterioration estimation device.

2. A deterioration estimation device for estimating deterioration of a secondary battery, comprising: a temperature acquisition unit that acquires a measured temperature of an outer surface of the secondary battery; a side reaction current calculation unit that calculates a side reaction current occurring at the negative electrode of the secondary battery using the acquired measured temperature; a coating thickness calculation unit that calculates the thickness of a coating formed on the negative electrode at a solid electrolyte interface using the side reaction current; a film resistance calculation unit that calculates a solid electrolyte interface film resistance, which is the resistance of the film at the solid electrolyte interface, as a deterioration index of the secondary battery using the film thickness, The side reaction current calculation unit calculates the side reaction current based on Equation 1, [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the coating thickness at the solid electrolyte interface, δ SEI (k-1) represents the coating thickness at the solid electrolyte interface calculated based on the previously obtained measurement temperature, δ SEI,INI represents a known initial value of the coating thickness at the solid electrolyte interface formed on the negative electrode, t 0 represents an aging treatment time indicating the storage period of the secondary battery, X in Equation 1 is a parameter defined in Equation 3, Y is a parameter defined in Equation 4, and Z is a parameter defined in Equation 5, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density of the solid electrolyte interface, [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, The coating thickness calculation unit calculates the coating thickness based on Equation 11, [0011] where k indicates the number of times the measured temperature is acquired, I SEI (k) is the side reaction current calculated by the side reaction current calculation unit using the measured temperature acquired the kth time, d W (k) represents the coating thickness calculated using the side reaction current I SEI (k), d W (k-1) represents the coating thickness calculated using the side reaction current I SEI (k-1), W(k) is a parameter defined by Equation 12, X is a parameter defined by Equation 3, and Δt represents the time interval for acquiring the measured temperature. [0012] where Y W is a parameter defined by Equation 13, Z W is a parameter defined by Equation 14, t 0 represents an aging treatment indicating the storage period of the secondary battery, δ SEI (k−1) represents the coating thickness at the solid electrolyte interface of the negative electrode calculated using a side reaction current based on the previously obtained measured temperature, δ SEI,INI represents a known initial value of the coating thickness at the solid electrolyte interface of the negative electrode, X is a parameter defined by Equation 3, Y is a parameter defined by Equation 4, and Z is a parameter defined by Equation 5, [0013] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [0014] where T [K] represents the measured temperature, A multi,w and B multi,w are predetermined coefficients, The film resistance calculation unit calculates the solid electrolyte interface film resistance based on Equation 16, [0016] where R SEI (k) represents the solid electrolyte interface coating resistance, k represents the number of times the measurement temperature is acquired, d W (k) is the coating thickness defined by Equation 11, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, and κ SEI represents the ionic conductivity in the coating at the solid electrolyte interface. Deterioration estimation device.

3. A deterioration estimation method for estimating deterioration of a secondary battery, comprising: acquiring a measured temperature of an outer surface of the secondary battery; Calculating a side reaction current occurring at the negative electrode of the secondary battery based on Equation 1; [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode, δ SEI (k-1) represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode calculated based on the measurement temperature previously obtained, δ SEI,INI represents a known initial value of the thickness of the coating at the solid electrolyte interface formed on the negative electrode, and t 0 represents an aging treatment time indicating the storage period of the secondary battery. In the above Equation 1, X is a parameter defined in Equation 3, Y is a parameter defined in Equation 4, and Z is a parameter defined in Equation 5, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density of the solid electrolyte interface, [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, Calculating the current ion concentration on the solid surface of the negative electrode based on Equation 6 and Equation 7; [Equation 6] [Equation 7] Here, c avg represents the average Li concentration of the active material, R p represents the radius of the active material, c s represents the Li concentration on the surface of the active material, D s represents the diffusion coefficient of Li in the solid phase of the negative electrode, and j Li SEI represents the ion flux on the solid phase surface of the secondary battery, and is defined by Equation 8: [Equation 8] where I SEI represents the side reaction current, a s represents the specific surface area of the active material, F is Faraday's constant, L p represents the thickness of the positive electrode of the secondary battery, L n represents the thickness of the negative electrode, and A represents the area of the coated portion of the negative electrode. calculating a decrease in the ion concentration on the solid phase surface of the negative electrode using the calculated current ion concentration on the solid phase surface of the negative electrode and a past ion concentration on the solid phase surface of the negative electrode calculated before the calculation of the current ion concentration; correcting a positive electrode OCP (Open Circuit Potential) in accordance with the calculated decrease in the ion concentration; calculating a first ion concentration corresponding to a potential difference between a positive electrode OCP and a negative electrode OCP when the SOC of the secondary battery is 0% and a second ion concentration corresponding to a potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 100%; Substituting the difference Li amo between the first ion concentration and the second ion concentration into Equation 9 to calculate the capacity of the secondary battery; [Equation 9] where F is the Faraday constant. Deterioration estimation method.

4. A degradation estimation method for estimating degradation of a secondary battery, comprising: acquiring a measured temperature of an outer surface of the secondary battery; Calculating a side reaction current of the secondary battery based on Equation 1; [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode of the secondary battery, δ SEI (k-1) represents the thickness of the coating at the solid electrolyte interface calculated based on the measurement temperature previously obtained, δ SEI,INI represents a known initial value of the thickness of the coating at the solid electrolyte interface, and t 0 represents an aging treatment time indicating the storage period of the secondary battery. In the above Equation 1, X is a parameter defined in Equation 3, Y is a parameter defined in Equation 4, and Z is a parameter defined in Equation 5, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density of the solid electrolyte interface, [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, Calculating the thickness of the coating at the solid electrolyte interface formed on the negative electrode using the side reaction current based on Equation 11; [0011] where k indicates the number of times the measured temperature has been acquired, I SEI (k) is the negative electrode side reaction current calculated using the measured temperature acquired the kth time, d W (k) represents the coating thickness calculated using the side reaction current I SEI (k), d W (k-1) represents the coating thickness calculated using the side reaction current I SEI (k-1), W(k) is a parameter defined by Equation 12, X is a parameter defined by Equation 3, and Δt represents the time interval for acquiring the measured temperature. [0012] where Y W is a parameter defined by Equation 13, Z W is a parameter defined by Equation 14, t 0 represents an aging treatment indicating the storage period of the secondary battery, δ SEI (k−1) represents the coating thickness at the solid electrolyte interface of the negative electrode calculated using a side reaction current based on the previously obtained measured temperature, δ SEI,INI represents a known initial value of the coating thickness at the solid electrolyte interface of the negative electrode, X is a parameter defined by Equation 3, Y is a parameter defined by Equation 4, and Z is a parameter defined by Equation 5, [0013] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [0014] where T [K] represents the measured temperature, A multi,w and B multi,w are predetermined coefficients, Calculating a solid electrolyte interface film resistance, which is the resistance of the film at the solid electrolyte interface, as a deterioration index of the secondary battery based on Equation 16; [0016] where R SEI (k) represents the solid electrolyte interface coating resistance, k represents the number of times the measurement temperature has been obtained, d W (k) is the coating thickness defined by Equation 11, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, and κ SEI represents the ionic conductivity in the coating at the solid electrolyte interface. Deterioration estimation method.

5. A deterioration estimation program for estimating deterioration of a secondary battery, the program comprising: obtaining a measured temperature of an exterior surface of the secondary battery; Calculating a side reaction current occurring at the negative electrode of the secondary battery based on Equation 1; [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode, δ SEI (k-1) represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode calculated based on the measurement temperature previously obtained, δ SEI,INI represents a known initial value of the thickness of the coating at the solid electrolyte interface formed on the negative electrode, and t 0 represents an aging treatment time indicating the storage period of the secondary battery. X in the above formula 1 is a parameter defined by formula 3, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density of the solid electrolyte interface, Y in the above formula 1 is defined by formula 4, [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, Z in the above formula 1 is defined by formula 5, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, Calculating the current ion concentration on the solid surface of the negative electrode based on Equation 6 and Equation 7; [Equation 6] [Equation 7] Here, c avg represents the average Li concentration of the active material, R p represents the radius of the active material, c s represents the Li concentration on the surface of the active material, D s represents the diffusion coefficient of Li in the solid phase of the negative electrode, and j Li SEI represents the ion flux on the solid phase surface of the secondary battery, and is defined by Equation 8: [Equation 8] where I SEI represents the side reaction current, a s represents the specific surface area of the active material, F is Faraday's constant, L p represents the thickness of the positive electrode of the secondary battery, L n represents the thickness of the negative electrode, and A represents the area of the coated portion of the negative electrode. calculating a decrease in the ion concentration on the solid phase surface of the negative electrode using the calculated current ion concentration on the solid phase surface of the negative electrode and a past ion concentration on the solid phase surface of the negative electrode calculated before the calculation of the current ion concentration; correcting a positive electrode OCP (Open Circuit Potential) in accordance with the calculated decrease in the ion concentration; calculating a first ion concentration corresponding to a potential difference between a positive electrode OCP and a negative electrode OCP when the SOC of the secondary battery is 0% and a second ion concentration corresponding to a potential difference between the positive electrode OCP and the negative electrode OCP when the SOC is 100%; and calculating a capacity of the secondary battery by substituting the difference Li amo between the first ion concentration and the second ion concentration into Equation 9; [Equation 9] where F is the Faraday constant. Deterioration estimation program.

6. A deterioration estimation program for estimating deterioration of a secondary battery, the program comprising: obtaining a measured temperature of an exterior surface of the secondary battery; Calculating a side reaction current of the secondary battery based on Equation 1; [Equation 1] where I SEI represents the side reaction current, k represents the number of times the measurement temperature has been obtained, δ SEI represents the thickness of the coating at the solid electrolyte interface formed on the negative electrode of the secondary battery, δ SEI (k-1) represents the thickness of the coating at the solid electrolyte interface calculated based on the measurement temperature previously obtained, δ SEI,INI represents a known initial value of the thickness of the coating at the solid electrolyte interface, and t 0 represents an aging treatment time indicating the storage period of the secondary battery. X in the above formula 1 is a parameter defined by formula 3, [Equation 3] where M SEI represents the molecular weight of the solid electrolyte interface, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, F is Faraday's constant, and ρ SEI represents the density of the solid electrolyte interface, Y in the above formula 1 is defined by formula 4, [Equation 4] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, Z in the above formula 1 is defined by formula 5, [Equation 5] where T [K] represents the measured temperature, A multi and B multi are predetermined coefficients, Calculating the thickness of the coating at the solid electrolyte interface formed on the negative electrode using the side reaction current based on Equation 11; [0011] where k indicates the number of times the measured temperature has been acquired, I SEI (k) is the negative electrode side reaction current calculated using the measured temperature acquired the kth time, d W (k) represents the coating thickness calculated using the side reaction current I SEI (k), d W (k-1) represents the coating thickness calculated using the side reaction current I SEI (k-1), W(k) is a parameter defined by Equation 12, X is a parameter defined by Equation 3, and Δt represents the time interval for acquiring the measured temperature. [0012] where Y W is a parameter defined by Equation 13, Z W is a parameter defined by Equation 14, t 0 represents an aging treatment indicating the storage period of the secondary battery, δ SEI (k−1) represents the coating thickness at the solid electrolyte interface of the negative electrode calculated using a side reaction current based on the previously obtained measured temperature, δ SEI,INI represents a known initial value of the coating thickness at the solid electrolyte interface of the negative electrode, X is a parameter defined by Equation 3, Y is a parameter defined by Equation 4, and Z is a parameter defined by Equation 5, [0013] where T [K] represents the measured temperature, A coeff and B coeff are predetermined coefficients, [0014] where T [K] represents the measured temperature, A multi,w and B multi,w are predetermined coefficients, and calculating a solid electrolyte interface film resistance, which is the resistance of the film at the solid electrolyte interface, as a deterioration index of the secondary battery based on Equation 16; [0016] where R SEI (k) represents the solid electrolyte interface coating resistance, k represents the number of times the measurement temperature has been obtained, d W (k) is the coating thickness defined by Equation 11, a s,n represents the specific surface area which is the ratio of the surface area to the volume of the active material of the negative electrode, A represents the area of the coated portion of the negative electrode, L n represents the thickness of the negative electrode, ε s,n represents the volume fraction of the negative electrode which is the ratio of the volume of the active material excluding voids to the volume of the active material including voids, and κ SEI represents the ionic conductivity in the coating at the solid electrolyte interface. Deterioration estimation program.

Images