Battery Performance Estimation Using Polarization Resistance
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Solution Overview
Problem
Existing methods struggle to accurately measure and estimate the output improvement of rechargeable batteries due to variations in measurement conditions such as state-of-charge (SOC), cut-off conditions, and temperature, making it difficult to assess the impact of ion movement speed improvements.
Innovation Solution
A device and method for estimating rechargeable battery performance by discharging the battery in constant current (CC) and constant voltage (CV) modes, quantifying polarization resistance (Rpola) based on discharge current output, and comparing it against a predetermined reference value to determine if the battery meets expected performance standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage and current are simultaneously measured and controlled to measure output of rechargeable battery, then measurement accuracy is improved, but device complexity and measurement difficulty increase significantly
Solution Approach 1:
The patent extracts and isolates the polarization resistance component from the total battery resistance by applying a specific current step and measuring only the instantaneous voltage response. This separates the measurement of ion movement resistance from other electrical characteristics, simplifying the measurement system while maintaining accuracy for the specific parameter of interest.
Solution Approach 2:
The patent changes the measurement parameter from simultaneous voltage-current measurement to sequential current-step application with voltage response measurement. By applying a current step ΔI and measuring the instantaneous voltage change ΔV, the system determines polarization resistance Rpola = ΔV/ΔI without requiring continuous simultaneous control of both parameters.
2Reliability
If multiple measurement conditions (output holding time, SOC, cut-off condition, temperature) are controlled to measure output, then measurement reliability is improved, but ease of operation deteriorates due to numerous constraints
Solution Approach 1:
The patent extracts the polarization resistance measurement from the complex set of output measurement conditions by focusing solely on the instantaneous response to a current step. This eliminates the need to control and record multiple parameters such as output holding time, SOC, and cut-off conditions, while still providing reliable data about ion movement characteristics.
Solution Approach 2:
The patent changes the measurement approach from monitoring multiple time-dependent parameters to capturing a single instantaneous voltage response. By measuring ΔV at the moment of current step application, the method achieves reliable results without requiring control over extended time periods or multiple operational conditions.
3Ease of operation
If conventional capacity measurement method is used, then ease of operation is maintained, but ability to assess ion movement speed improvement deteriorates
Solution Approach 1:
The patent changes the measured parameter from total capacity (integrated over time) to polarization resistance (instantaneous response). This parameter change enables direct assessment of ion movement speed while maintaining operational simplicity, as the measurement still involves basic voltage-current relationships but focuses on the specific aspect related to ion kinetics.
Solution Approach 2:
The patent substitutes the mechanical/integrated measurement approach (capacity measurement requiring charge/discharge cycles) with an electrical/response-based measurement (polarization resistance through instantaneous voltage response). This substitution maintains ease of operation while providing precise information about ion movement characteristics.
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 determination of whether a rechargeable battery meets predetermined output performance criteria by measuring polarization resistance (Rpola), facilitating research and production quality control.
Implementation Method 1
a rechargeable battery which is discharged with a constant current (CC) mode and a constant voltage (CV) mode
Implementation Method 2
improving a movement speed of ions... adding new materials to improve the movement speed of the ions (Li+)
Implementation Method 3
improving a movement speed of electrons... research on technology to increase conductivity to improve the movement speed of the electrons
Implementation Method 4
estimating the output improvement of the rechargeable battery according to the improvement of the movement speed of the ion based on a polarization resistance (Rpola), which is a resistance caused by the movement of the ions
Data Source
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AI summary
Discussed are a device, a system and a method for estimating a performance of a rechargeable battery. The device can include a current sensor to measure a discharge current output from a rechargeable battery during a discharge period in which the rechargeable battery is discharged from a predetermined reference voltage with a constant voltage, and a control circuit to calculate a resistance change relationship depending on a State of Charge (SOC) change during the discharge period based on the predetermined reference voltage and a change of the discharge current depending on time passage.