Secondary Battery Power Estimation Using Dynamic Resistance
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Solution Overview
Problem
Accurately estimating the power of a secondary battery with a blended cathode material is challenging due to its unique electrochemical behavior, which affects the battery's performance and requires a method to consider the distinct properties of the blended cathode materials.
Innovation Solution
An apparatus and method that measure the discharge current and estimate the state of charge of a secondary battery using predefined resistances corresponding to different discharge current conditions, allowing for the calculation of the battery's power based on the estimated discharge voltage and measured discharge current, taking into account the distinct operating voltage ranges of the blended cathode materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single cathode material is used, then manufacturing cost is reduced and structure is simplified, but it is impossible to satisfy all industrial performance standards (high energy capacity and high-temperature stability)
Solution Approach 1:
The patent uses a composite cathode material consisting of a first cathode material (Li-rich layered oxide) and a second cathode material (spinel structure) in a specific weight ratio range (70:30 to 30:70). This composite structure combines the high energy capacity of the Li-rich layered oxide with the high-temperature stability of the spinel structure, allowing the battery to meet multiple performance standards simultaneously while maintaining reasonable manufacturing complexity
2Reliability
If a blended cathode material is used, then high energy capacity and high-temperature stability are achieved, but the electrochemical behavior becomes unique and complex, making accurate power estimation difficult
Solution Approach 1:
The patent segments the cathode material into two distinct components with different electrochemical characteristics (first cathode material with higher operating voltage range and second cathode material with lower operating voltage range). By defining separate resistance parameters (first resistance and second resistance) corresponding to different state of charge ranges, the complex blended cathode behavior is divided into manageable segments that can be estimated using different resistance values for different SOC ranges
3Ease of operation
If a simple resistance estimation method is used, then calculation is simplified, but accurate power estimation is impossible for blended cathode materials with unique electrochemical behavior
Solution Approach 1:
The patent implements a dynamic resistance selection method where the resistance value used for power estimation changes based on the state of charge range. When SOC is in the first range (0-80%), the first resistance is used; when SOC is in the second range (80-100%), the second resistance is used. This dynamic approach maintains calculation simplicity through conditional logic while achieving accurate power estimation by selecting the appropriate resistance value for each SOC range
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables easy and accurate estimation of the secondary battery's power within the state of charge range where resistance changes occur, optimizing the battery's performance by considering the specific electrochemical properties of the blended cathode materials.
Implementation Method 1
A battery is a device that produces electrical energy through electrochemical oxidation and reduction reactions
Implementation Method 2
estimate a discharge voltage of the secondary battery using a first resistance predefined corresponding to the state of charge under a first condition in which a magnitude of the discharge current is smaller than a magnitude of a critical current
Data Source
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AI summary
Disclosed are an apparatus and method for estimating the power of a secondary battery including a blended cathode material. The apparatus according to the present disclosure includes a sensor configured to measure a discharge current of a secondary battery comprising a cathode including a blended cathode material, an anode, and a separator, the blended cathode material including at least a first cathode material and a second cathode material and an operating voltage range of the first cathode material being higher than an operating voltage range of the second cathode material, and a control unit configured to estimate a state of charge of the secondary battery, determine a discharge voltage of the secondary battery using a first resistance predefined corresponding to the state of charge under a first condition in which a magnitude of the discharge current is smaller than a magnitude of a critical current and a second resistance predefined corresponding to the state of charge under a second condition in which the magnitude of the discharge current is larger than the magnitude of the critical current, and determine the power of the secondary battery from the determined discharge voltage and the measured discharge current.