method AND APPARATUS for MEASURING RESISTANCE OF secondary battery

Abstract

A method and apparatus for measuring the resistance of a secondary battery are provided, comprising the steps of: maintaining the secondary battery at a predetermined temperature and a predetermined state of charge (SOC); pulse-discharging the secondary battery maintained at the predetermined state of charge (SOC) at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse-discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on the voltage drop measured during the first time period and the second time period.

Description

Technology Field

[0001] This description relates to a method and apparatus for measuring the resistance of a secondary battery. Background Technology

[0002] Rechargeable batteries generally consist of a positive electrode containing a positive active material, a negative electrode containing a negative active material, a separator, and an electrolyte, and charging and discharging can be performed through the intercalation and decalation of lithium ions. For example, lithium-ion rechargeable batteries are applied in various fields because they possess advantages such as high energy density, high electromotive force, and the ability to deliver high capacity.

[0003] To evaluate the performance of such secondary batteries, their resistance can be measured using methods such as HPPC (Hybrid Pulse Power Characterization). HPPC measurement simulates operation in actual usage environments by subjecting the secondary battery to high-output pulse discharge, through which the battery's internal resistance, output characteristics, and energy density can be identified. The problem to be solved

[0004] Some embodiments provide a method for measuring the resistance of a secondary battery.

[0005] Some embodiments provide a device for measuring the resistance of a secondary battery. means of solving the problem

[0006] According to some embodiments, a method for measuring the resistance of a secondary battery is provided. The method comprises the steps of: maintaining the secondary battery at a predetermined SOC at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse-discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on the voltage drop measured during the first time period and the second time period.

[0007] The step of determining the resistance of a secondary battery based on voltage drops measured during a first time and a second time in the above method may include the step of determining the internal resistance (ohmic resistance) of the secondary battery based on a first voltage drop measured during a first time, and the step of determining the diffusion resistance of the secondary battery based on a second voltage drop measured during a second time.

[0008] The step of determining the resistance of a secondary battery based on a first voltage drop measured during a first time period and a second voltage drop measured during a second time period in the above method may further include the step of determining the charge transfer resistance of the secondary battery based on a third voltage drop measured during a first time period.

[0009] In the above method, the third time may be longer than the first time.

[0010] In the above method, after the first time has elapsed, the terminal voltage of the secondary battery may be greater than the lower limit voltage of the secondary battery.

[0011] The step of pulse-discharging a secondary battery maintained at a predetermined SOC in the above method at a first discharge rate for a first time period comprises: a step of predicting whether the terminal voltage of the secondary battery reaches a lower limit voltage while the secondary battery is being discharged at the first discharge rate; and

[0012] The method may include a step of stopping pulse discharge when it is predicted that the terminal voltage of the secondary battery will reach a lower limit voltage.

[0013] According to some embodiments, a method for measuring the resistance of a secondary battery is provided. The method may include the steps of: maintaining the secondary battery at a predetermined SOC at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate; reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage; and determining the resistance of the secondary battery based on the voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate and the second discharge rate.

[0014] In the above method, the step of determining the resistance of a secondary battery based on a voltage drop measured while the secondary battery is pulse discharged at a first discharge rate and a second discharge rate may include the step of determining the ohmic resistance of the secondary battery based on a first voltage drop measured while the secondary battery is pulse discharged at a first discharge rate, the step of determining the charge transfer resistance of the secondary battery based on a second voltage drop measured while the secondary battery is pulse discharged at a first discharge rate, and the step of determining the diffusion resistance of the secondary battery based on a third voltage drop measured while the secondary battery is pulse discharged at a second discharge rate.

[0015] In the above method, the second pulse duration corresponding to the second discharge rate may be longer than the first pulse duration corresponding to the first discharge rate.

[0016] In the above method, the first pulse duration can be predetermined through experiment or simulation to a value at which the terminal voltage of the secondary battery does not reach a lower limit voltage.

[0017] In the above method, the step of reducing the first discharge rate to a second discharge rate and pulse discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage may include the step of monitoring the voltage drop while the secondary battery is pulse discharging at the first discharge rate, and the step of predicting that the terminal voltage will reach a lower limit voltage and changing the first discharge rate to the second discharge rate.

[0018] In the above method, the step of reducing the first discharge rate to a second discharge rate and pulse discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage may include the step of monitoring the voltage drop while the secondary battery is pulse discharging at the first discharge rate, and the step of changing the first discharge rate to the second discharge rate when the terminal voltage reaches a predetermined interval end voltage, and the predetermined interval end voltage may be greater than the lower limit voltage.

[0019] According to some embodiments, an apparatus for measuring the resistance of a secondary battery is provided. The apparatus comprises a control unit that maintains the secondary battery at a predetermined temperature and a predetermined state of charge (SOC), and pulse discharges the secondary battery maintained at the predetermined state of charge at a first discharge rate for a first time period, and a measuring unit that measures the terminal voltage of the secondary battery for a first time period. The control unit pauses the secondary battery for a second time period after the first time period, pulse discharges the paused secondary battery at a second discharge rate for a third time period, and determines the resistance of the secondary battery based on the voltage drop measured by the measuring unit during the first time period and the second time period.

[0020] According to some embodiments, an apparatus for measuring the resistance of a secondary battery is provided. The apparatus comprises a control unit that maintains the secondary battery at a predetermined temperature and a predetermined state of charge (SOC), and pulse discharges the secondary battery maintained at the predetermined SOC at a first discharge rate, and a measuring unit that measures the terminal voltage of the secondary battery during the pulse discharge. The control unit reduces the first discharge rate to a second discharge rate and pulse discharges the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage, and can determine the resistance of the secondary battery based on the voltage drop measured by the measuring unit while the secondary battery is pulse discharged at the first discharge rate and the second discharge rate. Effects of the invention

[0021] By individually calculating the internal resistance, charge transfer resistance, and diffusion resistance of the secondary battery through two pulse discharge steps, the resistance of the secondary battery can be accurately measured in a low-temperature environment. Brief explanation of the drawing

[0022] FIG. 1 shows a resistance measuring device according to some embodiments. Figure 2 shows the matching results of the measured low-temperature resistance and room-temperature resistance of several secondary batteries according to some embodiments. FIGS. 3 and FIGS. 4 illustrate a resistance measurement method according to some embodiments. FIGS. 5 and 6 illustrate a resistance measurement method according to some embodiments. FIG. 7 shows a resistance measuring device according to some embodiments. Specific details for implementing the invention

[0023] The embodiments of this description are described below with reference to the attached drawings so that those skilled in the art can easily implement them. However, this description may be implemented in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain this description in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification are denoted by similar reference numerals.

[0024] In this description, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0025] In this description, when a part is described as "including" a certain component, it means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0026] Expressions written in the singular in this description may be interpreted as singular or plural unless explicit expressions such as "one" or "singular" are used.

[0027] In this description, "and / or" includes each of the mentioned components and all combinations of one or more.

[0028] In this description, terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present disclosure, the first component may be named the second component, and similarly, the second component may be named the first component.

[0029] In the flowchart described herein with reference to the drawings, the order of operations may be changed, multiple operations may be merged or some operations may be divided, and certain operations may not be performed.

[0030] The Artificial Intelligence model (AI model) of the present disclosure is a machine learning model that learns at least one task and may be implemented as a computer program executed by a processor. The task learned by the AI ​​model may refer to a problem to be solved through machine learning or a task to be performed through machine learning. The AI ​​model may be implemented as a computer program executed on a computing device, downloaded via a network, or sold in the form of a product. Alternatively, the AI ​​model may be linked with various devices via a network.

[0031] FIG. 1 shows a resistance measuring device according to some embodiments.

[0032] In some embodiments, the resistance measuring device (100) may determine the resistance of a secondary battery by performing a resistance measuring method comprising a first pulse discharge step, a resting step, and a second pulse discharge step. The resistance measuring device (100) may perform each step of the resistance measuring method using a predetermined set of parameters, wherein the set of parameters may include parameters such as the state of charge (SOC) of the secondary battery, pulse duration, and charge / discharge rate (C-rate).

[0033] In some embodiments, the resistance measuring device (100) can measure the resistance of a secondary battery in a low-temperature environment. At this time, the resistance measuring device (100) can evaluate the reliability of the measurement of the low-temperature resistance of the secondary battery by comparing it with the room-temperature resistance previously measured by other methods. For example, the resistance measuring device (100) measures the low-temperature resistance of several secondary batteries and the coefficient of determination (e.g., R) between the measured low-temperature resistance and the room-temperature resistance of the secondary battery. 2 The measurement reliability of low-temperature resistance can be evaluated based on the score.

[0034] Figure 2 shows the matching results of the measured low-temperature resistance and room-temperature resistance of several secondary batteries according to some embodiments.

[0035] Referring to FIG. 2, it can be seen that the matching rate is determined differently depending on the parameter set used in the resistance measurement method. In FIG. 2, each point on the graph represents an individual secondary battery, and the distribution of low-temperature resistance and room-temperature resistance of each of the multiple secondary batteries is R 2 Determine the score.

[0036] Referring to Fig. 2, the low-temperature resistance measured for a secondary battery using parameter sets of different SOCs (SOC X, SOC Y, or SOC Z) and discharge rates (0.5C or 1C, etc.) shows a different matching rate with the room-temperature resistance (in the experiment, when the SOC of the parameter set is low and the discharge rate is high, R2 (The score tends to be high). Therefore, in some embodiments, an optimal set of parameters for accurately measuring low-temperature resistance can be predetermined.

[0037] In some embodiments, the resistance measuring device (100) can maintain the secondary battery at a relatively low SOC at a low temperature and perform resistance measurements at a relatively high discharge rate. Referring to Table 1 below, it can be seen that the resistance of the secondary battery is measured more accurately when pulse discharge is performed at a relatively low SOC and a relatively high discharge rate.

[0038] parameter set R 2 Pulse duration (seconds) C-rate SOC 10 seconds 0.5 10 0.6463 20 0.4808 30 0.4017 1 10 0.6847 20 0.5381 30 0.4281 2 10 0.6871 20 0.6061 30 0.4579 2.5 10 0.6962 20 0.6289 30 0.4848

[0039] Table 1 shows the low-temperature resistance measurement results for a monocell with a capacity of 36 mAh, for example, 2.5 C indicates that a current of 90 mA is pulsed discharged for 10 seconds.

[0040] This is believed to be because the resistance of the secondary battery increases as the SOC decreases, and the effects of polarization and reduced ion mobility increase further at low temperatures. At an SOC of 30, it is believed that the coefficient of determination decreases because the resistance response pattern changes due to increased influences such as interfacial reactions and diffusion within the secondary battery. Additionally, the above results are due to the small change in resistance at low discharge rates, and this trend may be further intensified at low temperatures.

[0041] However, when the pulse duration is long, the matching rate with room temperature resistance increases (see Table 2), but resistance measurement may be difficult as the terminal voltage of the secondary battery reaches the lower limit voltage while the pulse is sustained.

[0042] Referring to Table 2, when pulse discharge is performed at a low SOC (SOC 10), the voltage drop is rapid, and the secondary battery reaches a lower limit voltage (2V) while the pulse is sustained, so the resistance is not measured.

[0043] In addition, if the pulse duration is short at 0.2s, only the IR drop caused by the internal resistance of the secondary battery is reflected, so it is judged that the matching rate with the room temperature resistance, which includes the influence of other resistances, is low. If the pulse duration is relatively long, resistances caused by slow reactions such as interface resistance and diffusion resistance are also measured, so it is judged that the matching rate with the room temperature resistance is high, but the pulse duration cannot be set long at low SOC.

[0044] parameter set R 2 SOC C-rate Pulse duration (seconds) 10 0.5 0.2 0.3938 10 0.6463 30 0.6295 1 0.2 0.1934 10 0.6847 30 - 2 0.2 0.292 10 0.6871 30 - 2.5 0.2 0.2672 10 0.6962 30 -

[0045] Accordingly, a resistance measuring device (100) according to some embodiments can measure the resistance of a secondary battery maintained at a low SOC in a low-temperature environment through a two-stage pulse discharge.

[0046] Referring to FIG. 1, a resistance measuring device (100) of a secondary battery according to some embodiments may include a control unit (110) and a measuring unit (120).

[0047] In some embodiments, the control unit (110) can perform each step for measuring the resistance of the secondary battery by maintaining the secondary battery at a predetermined temperature and a predetermined SOC, and then controlling the charging or discharging of the secondary battery for a predetermined time at a predetermined charging rate / discharging rate.

[0048] For example, in the first pulse discharge step, the control unit (110) can pulse discharge a secondary battery maintained at a predetermined SOC at a predetermined temperature for a first time at a first discharge rate. After the first pulse discharge step ends, in the resting step, the control unit (110) can rest the secondary battery for a second time. After the resting step ends, in the second pulse discharge step, the control unit (110) can pulse discharge at a second discharge rate for a third time. The first discharge rate and the second discharge rate may be of the same magnitude.

[0049] In some embodiments, the measuring unit (120) may measure the terminal voltage in real time during the pulse discharge phase of the secondary battery and provide the magnitude of the measured terminal voltage to the control unit (110). Additionally, the measuring unit (120) may monitor the temperature and / or SOC of the secondary battery and transmit this to the control unit (110).

[0050] In some embodiments, the control unit (110) may determine the resistance of the secondary battery based on the terminal voltage of the secondary battery measured by the measurement unit (120). For example, the control unit (110) may determine the ohmic resistance of the secondary battery based on the voltage drop measured during the first pulse discharge step. Additionally, the control unit (110) may determine the charge transfer resistance of the secondary battery based on another voltage drop measured during the first pulse discharge step. Additionally, the control unit (110) may determine the diffusion resistance of the secondary battery based on the voltage drop measured during the second pulse discharge step.

[0051] FIGS. 3 and FIGS. 4 illustrate a resistance measurement method according to some embodiments.

[0052] Referring to FIG. 3, the control unit (110) maintains the secondary battery at a predetermined temperature and a predetermined SOC (S110).

[0053] In some embodiments, the control unit (110) can maintain the secondary battery at a predetermined SOC at a low temperature of 0 degrees Celsius or lower. For example, the control unit (110) can maintain the secondary battery at an SOC of 10 at -10°C or -20°C.

[0054] As explained above, since the low-temperature resistance of a secondary battery maintained at a relatively low SOC can exhibit a high matching rate with the room-temperature resistance, the SOC of the secondary battery can be maintained at a relatively low level. In some embodiments, the risk that the terminal voltage of the secondary battery will reach a lower limit voltage before the discharge pulse ends when the secondary battery with a low SOC is discharged can be eliminated through two-stage pulse discharge.

[0055] In some embodiments, the parameter set for measuring low-temperature resistance may be predetermined by taking into account the lower limit voltage of the secondary battery. For example, if it is predicted that the secondary battery will easily reach the lower limit voltage at a relatively low temperature, the SOC of the secondary battery may be set to be maintained relatively high, or a relatively shorter pulse duration may be set, or a relatively lower discharge rate may be set.

[0056] Referring to FIG. 3, the control unit (110) can pulse discharge a secondary battery maintained at a predetermined SOC at a predetermined temperature at a first discharge rate for a first time (first pulse discharge step) (S120). In some embodiments, the first pulse discharge step may be performed to measure the internal resistance and charge transfer resistance of the secondary battery. For example, the control unit (110) can pulse discharge a secondary battery maintained at an SOC of 10 at -10°C at 2.5C for 10 seconds.

[0057] Referring to FIG. 4, the control unit (110) can pulse discharge the secondary battery at 2.5C for 60 to 70 seconds, and the measuring unit (120) can measure the voltage drop occurring during the first pulse discharge step. In FIG. 4, the measuring unit (120) can measure that a voltage drop from 3.5V to 2.8V occurred for a short period of several milliseconds (less than 1 second) immediately after the 60-second mark, and can measure that an additional voltage drop to 2.0V occurred for 10 seconds thereafter.

[0058] In some embodiments, the control unit (110) may adjust the parameters of the pulse discharge step (i.e., the SOC of the secondary battery, the pulse duration, and / or the discharge rate (C-rate)) in consideration of the lower limit voltage of the secondary battery. For example, when the first pulse discharge step is executed with a parameter set of SOC 10, 2.5C, and 10 seconds, the control unit (110) may stop the pulse discharge if it is predicted that the terminal voltage of the secondary battery will reach the lower limit voltage even before the pulse duration of 10 seconds has elapsed.

[0059] Referring to FIG. 3, the control unit (110) can rest the secondary battery for a second time after a first time (resting step) (S130). In some embodiments, by resting the secondary battery for a second time, the concentration gradient and ion distribution at the interface between the electrode and the electrolyte inside the secondary battery can approach an equilibrium state and the terminal voltage can be stabilized.

[0060] In some embodiments, the second time during which the secondary battery is idle may be predetermined based on the SOC of the secondary battery, the pulse duration, and / or the discharge rate of the first pulse discharge. For example, if a pulse discharge of 10 seconds is carried out at a discharge rate of 2.5C for a secondary battery with an SOC of 10, at least 1 minute may be required for the terminal voltage of the secondary battery to stabilize, so the second time required for the idle of the secondary battery may be predetermined to be 1 minute or more.

[0061] However, the resting phase may end after the terminal voltage of the secondary battery has sufficiently stabilized. For example, the resting phase may not exceed 3 minutes. Referring to FIG. 4, the control unit (110) may rest the secondary battery for 180 seconds (3 minutes) after the 70-second mark.

[0062] Due to the resting phase following the first pulse discharge phase, the secondary battery moves out of the transient state following the first pulse discharge and the terminal voltage of the secondary battery approaches equilibrium, thereby allowing the voltage drop due to diffusion resistance to be measured more accurately. If the resting phase is set too short, the voltage drop for calculating the diffusion resistance in the subsequent second pulse discharge phase may be measured inaccurately due to the influence of the first pulse discharge (concentration gradient, incomplete voltage recovery, etc.).

[0063] Referring to FIG. 3, the control unit (110) can pulse discharge the idle secondary battery at a second discharge rate for a third time (second pulse discharge step) (S140).

[0064] In some embodiments, the pulse duration of the second pulse discharge step (third time) may be longer than the pulse duration of the first pulse discharge step (first time). For example, the control unit (110) may perform a pulse discharge of the secondary battery for 10 seconds (first pulse discharge step), and after a resting step, perform a pulse discharge of the secondary battery for 20 seconds (second pulse discharge step).

[0065] In some embodiments, the control unit (110) may adjust the parameters of the pulse discharge step (i.e., the SOC of the secondary battery, the pulse duration, and / or the discharge rate (C-rate)) in consideration of the lower limit voltage of the secondary battery. For example, when the second pulse discharge step is executed with a parameter set of SOC 10, 2.5C, and 20 seconds, the control unit (110) may stop the pulse discharge if it is predicted that the terminal voltage of the secondary battery will reach the lower limit voltage even before the pulse duration of 20 seconds has elapsed. Subsequently, the parameter set may be adjusted and the second pulse discharge step may be performed using the adjusted parameter set.

[0066] In some embodiments, a second pulse discharge step is performed after a sufficient resting step, thereby mitigating the surface concentration gradient between the electrode and the electrolyte in the secondary battery, and allowing the diffusion resistance caused by the second pulse discharge to be measured individually.

[0067] Referring to FIG. 3, the control unit (110) can determine the resistance of the secondary battery based on the voltage drop measured by the measurement unit (120) during the first pulse discharge step and the second pulse discharge step (S150).

[0068] Referring to FIG. 4, the control unit (110) can determine the internal resistance and charge transfer resistance of the secondary battery, respectively, based on two voltage drops (3.5V→2.8V, 2.8V→2.0V) measured in the first pulse discharge step (2.5C). The internal resistance and charge transfer resistance of the secondary battery can be determined as shown in Equations 1 and 2 below, respectively.

[0069]

[0070]

[0071] Referring to FIG. 4, the control unit (110) can determine the diffusion resistance of the secondary battery based on the voltage drop (3.4V→2.0V) measured in the second pulse discharge stage (2.5C). Since a rapid voltage drop due to internal resistance occurs even in the second pulse discharge stage (3.4V→3.1V), the corresponding voltage drop can be excluded from the calculation so as not to affect the determination of the diffusion resistance, and thus the voltage drop corresponding to the diffusion resistance may be the portion reduced from 3.1V to 2.0V. The diffusion resistance of the secondary battery can be determined as shown in Equation 3 below.

[0072]

[0073] In some embodiments, when the control unit (110) predicts that the terminal voltage of the secondary battery will reach a lower limit voltage during the first pulse discharge stage and stops the pulse discharge, a portion of the voltage drop measured during the second pulse discharge stage may be used to calculate the charge transfer resistance.

[0074] As described above, the resistance measuring device (100) according to some embodiments can accurately measure the resistance of a secondary battery in a low-temperature environment by individually calculating the internal resistance, charge transfer resistance, and diffusion resistance of the secondary battery through two pulse discharge steps.

[0075] FIGS. 5 and 6 illustrate a resistance measurement method according to some embodiments.

[0076] Referring to FIG. 5, the control unit (110) maintains the secondary battery at a predetermined SOC at a predetermined temperature (S210). In some embodiments, the control unit (110) may maintain the secondary battery at a predetermined SOC at a low temperature of 0 degrees Celsius or lower. For example, the control unit (110) may maintain the secondary battery at an SOC of 10 at -10°C or -20°C.

[0077] As explained above, since the low-temperature resistance of a secondary battery maintained at a relatively low SOC can exhibit a high matching rate with the room-temperature resistance, the SOC of the secondary battery can be maintained at a relatively low value. In some embodiments, the risk that the terminal voltage of the secondary battery will reach a lower limit voltage before the discharge pulse ends when the secondary battery with a low SOC is discharged can be eliminated by reducing the discharge rate before the lower limit voltage is reached.

[0078] Referring to FIG. 5, the control unit (110) can pulse discharge a secondary battery maintained at a predetermined SOC at a predetermined temperature at a first discharge rate for a first time (first pulse discharge interval) (S220). For example, the control unit (110) can pulse discharge a secondary battery maintained at an SOC of 10 at -10℃ at 2.5C during the first pulse discharge interval. In some embodiments, the voltage drop measured during the first pulse discharge interval may be used to determine the internal resistance and charge transfer resistance of the secondary battery.

[0079] In some embodiments, the control unit (110) can pulse discharge the secondary battery to 2.5C starting from the 30-second mark, and the measuring unit (120) can measure the voltage drop occurring during the first pulse discharge interval. In FIG. 6, the measuring unit (120) can measure that a voltage drop from 3.5V to 2.8V occurred during a short period of several milliseconds (less than 1 second) immediately after the 30-second mark, and can subsequently measure an additional voltage drop to 2.2V.

[0080] In some embodiments, the control unit (110) may perform pulse discharge of a first pulse discharge interval for a predetermined time (e.g., 10 seconds) considering the lower limit voltage of the secondary battery. Here, the predetermined time represents the pulse duration during the first pulse discharge interval and may be predetermined as the length of time during which the terminal voltage of the secondary battery does not reach the lower limit voltage when the secondary battery is pulse discharged at a first discharge rate at a specific temperature. For example, the pulse duration of the first pulse discharge interval may be predetermined as a value during which the terminal voltage of the secondary battery does not reach the lower limit voltage through multiple repeated experiments or simulations.

[0081] In some embodiments, the control unit (110) may terminate the first pulse discharge section by considering the lower limit voltage of the secondary battery. The control unit (110) may terminate the pulse discharge of the first pulse discharge section after monitoring the voltage drop measured by the measurement unit (120) and predicting that the terminal voltage of the secondary battery will reach the lower limit voltage. Alternatively, the control unit (110) may terminate the pulse discharge of the first pulse discharge section after monitoring that the terminal voltage of the secondary battery has reached a predetermined section termination voltage (e.g., 2.2V, which is greater than the lower limit voltage of 2.0V) through the voltage drop measured by the measurement unit (120).

[0082] Referring to FIG. 5, the control unit (110) can reduce the discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage and pulse discharge the secondary battery at the reduced second discharge rate (second pulse discharge interval) (S230).

[0083] In some embodiments, the pulse duration of the second pulse discharge section may be longer than the pulse duration of the first pulse discharge section. For example, the control unit (110) may perform pulse discharge of the secondary battery at 2.5C for 10 seconds (first pulse discharge section), and perform pulse discharge of the secondary battery at a reduced discharge rate of 0.1C (second pulse discharge section) before the terminal voltage of the secondary battery reaches a lower limit voltage.

[0084] In some embodiments, the discharge rate of the pulse discharge is lowered (e.g., 2.5C→0.1C) before the terminal voltage of the secondary battery reaches the lower limit voltage, thereby preventing the risk of the terminal voltage of the secondary battery reaching the lower limit voltage in advance, and the diffusion resistance of the secondary battery can also be accurately measured.

[0085] Referring to FIG. 5, the control unit (110) can determine the resistance of the secondary battery based on the voltage drop measured by the measurement unit (120) during the first pulse discharge period and the second pulse discharge period (S240).

[0086] Referring to FIG. 6, the control unit (110) can determine the internal resistance and charge transfer resistance of the secondary battery, respectively, based on two voltage drops (3.5V→2.8V, 2.8V→2.2V) measured during the first pulse discharge interval (2.5C, 10 seconds). The internal resistance and charge transfer resistance of the secondary battery can be determined as shown in Equations 4 and 5 below, respectively.

[0087]

[0088]

[0089] Referring to FIG. 6, the control unit (110) can determine the diffusion resistance of the secondary battery based on the voltage drop (2.2V→2.0V) measured during the second pulse discharge interval (0.1C, 20 seconds). The diffusion resistance of the secondary battery can be determined as shown in Equation 6 below.

[0090]

[0091] As described above, the resistance measuring device (100) according to some embodiments can accurately measure the resistance of a secondary battery in a low-temperature environment by individually calculating the internal resistance, charge transfer resistance, and diffusion resistance of the secondary battery through two pulse discharge sections divided according to the lower limit voltage.

[0092] FIG. 7 shows a control unit of a resistance measuring device according to some embodiments.

[0093] A control unit of a resistance measuring device according to some embodiments may be implemented as a computer system, for example, a computer-readable medium. Referring to FIG. 7, the computer system (700) may include at least one of a processor (710) communicating via a bus (770), a memory (730), an input interface device (750), an output interface device (760), and a storage device (740). The computer system (700) may also include a communication device (720) coupled to a network.

[0094] At least one processor (710) may be a central processing unit (CPU) or a semiconductor device that executes instructions stored in memory (730) or a storage device (740). The processor (710) may implement the function, process, or method proposed in the embodiment. The operation of the computer system (700) according to the embodiment may be implemented by the processor (710). At least one processor (710) may include at least one of a GPU, a CPU, and an NPU. When the operation of the computer system (700) is implemented by at least one processor (710), each task may be divided among at least one processor (710) according to the load. For example, when one processor is a CPU, the other processor may be any one of a GPU, an NPU, an FPGA, or a DSP.

[0095] The memory (730) and storage device (740) may include various forms of volatile or non-volatile storage media. For example, the memory may include ROM (read only memory) and RAM (random access memory). The memory (730) may be connected to the processor (710) and may store various information for driving the processor (710) or at least one program executed by the processor (710). Alternatively, the memory (730) may store instructions that cause the processor (710) to perform a plurality of steps included in the function, process, or method proposed in the embodiment.

[0096] In the embodiments of the present description, the memory may be located inside or outside the processor, and the memory may be connected to the processor through various known means. The memory is a volatile or non-volatile storage medium of various forms, and, for example, the memory may include read-only memory (ROM) or random access memory (RAM).

[0097] Accordingly, the embodiments may be implemented as a method implemented on a computer or as a non-transient computer-readable medium storing computer-executable instructions. In some embodiments, when executed by a processor, the computer-readable instructions may perform the method according to at least one aspect of the present description.

[0098] The communication device (720) can transmit or receive wired or wireless signals.

[0099] Meanwhile, the embodiments are not implemented solely through the devices and / or methods described so far, but may also be implemented through a program that realizes a function corresponding to the configuration of the embodiments or a recording medium on which such a program is recorded. Such implementation can be easily achieved by a person skilled in the art to which the present invention pertains, based on the description of the embodiments described above. Specifically, the method according to the embodiments (e.g., network management method, data transmission method, transmission schedule generation method, etc.) may be implemented in the form of program instructions that can be executed through various computer means and may be recorded on a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, etc., either individually or in combination. The program instructions recorded on the computer-readable medium may be specially designed and configured for the embodiments, or they may be known and available to a person skilled in the art of computer software. The computer-readable recording medium may include a hardware device configured to store and execute program instructions. For example, computer-readable recording media may be magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floptical disks; ROM; RAM; flash memory; etc. Program instructions may include machine code, such as that generated by a compiler, as well as high-level language code that can be executed by a computer through an interpreter, etc.

[0100] Although the embodiments have been described in detail above, the scope of the rights is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concepts defined in the following claims are also included within the scope of the rights.

Claims

Claim 1 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse-discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on voltage drops measured during the first time period and the second time period. The step of determining the resistance of the secondary battery based on voltage drops measured during the first time period and the second time period comprises: determining the ohmic resistance of the secondary battery based on the first voltage drop measured during the first time period; and determining the diffusion resistance of the secondary battery based on the second voltage drop measured during the second time period. Claim 2 delete Claim 3 A method according to claim 1, wherein the step of determining the resistance of the secondary battery based on a first voltage drop measured during the first time and a second voltage drop measured during the second time further comprises the step of determining the charge transfer resistance of the secondary battery based on a third voltage drop measured after the first voltage drop during the first time. Claim 4 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse-discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on the voltage drop measured during the first time period and the second time period, wherein the third time period is longer than the first time period. Claim 5 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse-discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on the voltage drop measured during the first time period and the second time period, wherein after the first time period has elapsed, the terminal voltage of the secondary battery is greater than the lower limit voltage of the secondary battery. Claim 6 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; resting the secondary battery for a second time period after the first time period; pulse discharging the rested secondary battery at a second discharge rate for a third time period; and determining the resistance of the secondary battery based on the voltage drop measured during the first time period and the second time period. The step of pulse discharging the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period comprises the step of predicting whether the terminal voltage of the secondary battery reaches a lower limit voltage while the secondary battery is being discharged at the first discharge rate, and the step of stopping the pulse discharge if it is predicted that the terminal voltage of the secondary battery will reach the lower limit voltage. Claim 7 A method for measuring the resistance of a secondary battery comprises the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate; reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage; and determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate and the second discharge rate. The step of determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate and the second discharge rate comprises: determining the internal resistance (ohmic resistance) of the secondary battery based on a first voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate; and after the first voltage drop while the secondary battery is pulse-discharging at the first discharge rate. A method comprising the step of determining the charge transfer resistance of the secondary battery based on a second voltage drop measured. Claim 8 In claim 7, the step of determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse discharged at the first discharge rate and the second discharge rate further comprises the step of determining the diffusion resistance of the secondary battery based on a third voltage drop measured while the secondary battery is pulse discharged at the second discharge rate. Claim 9 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate; reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage; and determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse-discharged at the first discharge rate and the second discharge rate, wherein the second pulse duration corresponding to the second discharge rate is longer than the first pulse duration corresponding to the first discharge rate. Claim 10 In claim 9, the method wherein the first pulse duration is predetermined through experiment or simulation to a value such that the terminal voltage of the secondary battery does not reach the lower limit voltage. Claim 11 A method for measuring the resistance of a secondary battery, comprising the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate; reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage; and determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate and the second discharge rate. The step of reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage comprises the steps of: monitoring the voltage drop while the secondary battery is pulse-discharging at the first discharge rate; and predicting that the terminal voltage will reach the lower limit voltage and changing the first discharge rate to the second discharge rate. Claim 12 A method for measuring the resistance of a secondary battery comprises the steps of: maintaining the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature; pulse-discharging the secondary battery maintained at the predetermined SOC at a first discharge rate; reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage; and determining the resistance of the secondary battery based on a voltage drop measured while the secondary battery is pulse-discharging at the first discharge rate and the second discharge rate. The step of reducing the first discharge rate to a second discharge rate and pulse-discharging the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage comprises the steps of: monitoring the voltage drop while the secondary battery is pulse-discharging at the first discharge rate; and changing the first discharge rate to the second discharge rate when the terminal voltage reaches a predetermined interval end voltage. The predetermined interval A method in which the termination voltage is greater than the lower limit voltage. Claim 13 A device for measuring the resistance of a secondary battery, comprising: a control unit that maintains the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature and pulse discharges the secondary battery maintained at the predetermined SOC at a first discharge rate for a first time period; and a measuring unit that measures the terminal voltage of the secondary battery during the first time period. The control unit, wherein the secondary battery is paused for a second time period after the first time period, pulse discharges the paused secondary battery at a second discharge rate for a third time period, determines the ohmic resistance of the secondary battery based on a first voltage drop measured by the measuring unit during the first time period, and determines the charge transfer resistance of the secondary battery based on a second voltage drop measured by the measuring unit after the first voltage drop during the first time period. Claim 14 A device for measuring the resistance of a secondary battery, comprising: a control unit that maintains the secondary battery at a predetermined state of charge (SOC) at a predetermined temperature and pulse discharges the secondary battery maintained at the predetermined SOC at a first discharge rate; and a measuring unit that measures the terminal voltage of the secondary battery during the pulse discharge. The control unit reduces the first discharge rate to a second discharge rate and pulse discharges the secondary battery at the second discharge rate before the terminal voltage of the secondary battery reaches a lower limit voltage. The device determines the ohmic resistance of the secondary battery based on a first voltage drop measured by the measuring unit while the secondary battery is pulse discharged at the first discharge rate, and determines the diffusion resistance of the secondary battery based on a second voltage drop measured by the measuring unit while the secondary battery is pulse discharged at the second discharge rate.

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