Battery State Determination via Complex Impedance Analysis
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Solution Overview
Problem
Existing methods for determining the state of rechargeable batteries, such as those used in hybrid and electric vehicles, are inadequate for accurately assessing conditions beyond discharge reserve, making it difficult to determine whether these batteries can be reused effectively.
Innovation Solution
A method involving complex impedance analysis is used to determine the state of rechargeable batteries by measuring complex impedance with AC voltage or current, identifying shifts in negative and positive electrode capacities through specific threshold comparisons, allowing for targeted reconditioning processes to enhance reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex impedance analysis is performed using conventional methods, then the discharge reserve of the battery can be determined, but other battery conditions such as electrode capacity shifts cannot be accurately assessed
Solution Approach 1:
The patent segments the battery assessment into distinct components: negative electrode capacity shift detection, positive electrode capacity shift detection, and discharge reserve determination. Each component is evaluated using specific impedance parameters (imaginary axis level for negative electrode, gradient for positive electrode), enabling comprehensive multi-dimensional battery state assessment beyond conventional single-parameter analysis
Solution Approach 2:
The patent extends the assessment from conventional discharge reserve only to multiple dimensions by utilizing different aspects of complex impedance: the level of the imaginary axis for negative electrode capacity shift and the gradient of the complex impedance for positive electrode capacity shift. This multi-dimensional approach enables simultaneous evaluation of multiple battery conditions
2Device complexity
If conventional impedance analysis is used, then the assessment process is simple, but the ability to distinguish between negative and positive electrode capacity shifts is insufficient
Solution Approach 1:
The patent applies local quality by assigning specific evaluation criteria to specific electrode types: the level of the imaginary axis of complex impedance is used specifically for negative electrode capacity shift detection, while the gradient of complex impedance is used specifically for positive electrode capacity shift detection. This targeted approach enables precise differentiation between the two types of capacity shifts without requiring complex additional equipment
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
This approach enables more accurate determination of battery states, allowing for specific reconditioning adjustments that increase the reusability of batteries by distinguishing between negative and positive electrode capacity shifts, thereby extending the life and usability of rechargeable batteries.
Implementation Method 1
Complex impedance analysis is performed to determine the state of a battery. This technique allows the battery state to be determined without destroying the battery.
Data Source
AI summary
A method for determining a state of a rechargeable battery includes obtaining a complex impedance measured by applying AC voltage or AC current to a rechargeable battery that is subject to determination and determining a state of the rechargeable battery based on the obtained complex impedance. The determining a state of the rechargeable battery includes determining whether or not a first capacity shift is occurring based on a comparison of a value of the complex impedance at a predetermined frequency with a first determination value used to determine a negative electrode capacity shift, and when determined that the first capacity shift is not occurring, determining whether or not a second capacity shift is occurring based on a comparison of a gradient of the complex impedance with respect to a real axis in a diffusion resistance region with a second determination value used to determine a positive electrode capacity shift.