Secondary Battery State Detection via dV/dQ Derivative Analysis
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Solution Overview
Problem
Existing secondary battery systems face challenges in accurately detecting the state, particularly the charging state and deterioration state, especially when the change in battery voltage is small, leading to potential misinterpretation of the battery's condition.
Innovation Solution
The use of a secondary battery system with a first active material that undergoes phase changes during charge and discharge, combined with a second active material that performs two-phase coexistence type charge and discharge, allows for accurate detection through the analysis of characteristic points in Q-dV/dQ and V-dV/dQ curves, enabling precise determination of the battery's state, including charging state, deterioration, and abnormality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a secondary battery uses an active material with stable output characteristics and small voltage variation, then output stability is improved, but state detection accuracy deteriorates
Solution Approach 1:
The patent changes the detection parameter from battery voltage (V) to the derivative dV/dQ (rate of change of voltage with respect to charge). This parameter transformation allows accurate state detection even when voltage variation is small, as dV/dQ amplifies the subtle changes in voltage that occur during charge-discharge cycles of stable batteries.
Solution Approach 2:
The patent replaces the conventional voltage-based detection method with a derivative-based detection method. By calculating dV/dQ from measured voltage and charge data, the system substitutes a mathematical transformation approach for direct voltage threshold comparison, enabling precise detection of battery state characteristics.
2Stability of the object's composition
If battery voltage change amount is small, then output stability is improved, but charging state detection accuracy deteriorates
Solution Approach 1:
The patent transforms the detection parameter from absolute voltage values to the rate of change dV/dQ. This parameter change converts small absolute voltage variations into detectable derivative values, allowing accurate charging state detection even when voltage stability is high and voltage change amount is small.
Solution Approach 2:
The patent introduces a new dimension of analysis by using the derivative dV/dQ instead of working solely with voltage values. This dimensional transformation from V to dV/dQ space creates enhanced sensitivity to charging state changes, effectively adding a derivative dimension to the detection methodology.
3Stability of the object's composition
If a secondary battery exhibits small voltage change over wide capacity range, then output characteristics are stabilized, but deterioration detection accuracy deteriorates
Solution Approach 1:
The patent applies parameter transformation from voltage (V) to voltage derivative (dV/dQ) to detect battery deterioration. This parameter change enables the detection of subtle degradation patterns in the dV/dQ characteristics that would be imperceptible in the stable voltage profile, allowing deterioration detection despite small voltage changes.
Solution Approach 2:
The patent uses dV/dQ characteristics as feedback to monitor battery health. By continuously analyzing the derivative values during charge-discharge cycles, the system obtains feedback on battery state that reveals deterioration patterns, enabling accurate detection even when voltage stability masks the degradation in conventional voltage measurements.
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 allows for accurate detection of the battery's state, including charging state, deterioration, and abnormality, even in scenarios with small voltage changes, thereby ensuring reliable monitoring and maintenance of the battery's performance.
Implementation Method 1
the first active material that makes a phase change by charge and discharge
Data Source
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AI summary
Provided is a secondary battery system which can accurately detect a state of a secondary battery system (such as a secondary battery state and a secondary battery system failure). The secondary battery system (6) includes dV/dQ calculation means which calculates a dV/dQ value as a ratio of a change amount dV of a battery voltage V of a secondary battery (100) against a change amount dQ of an accumulation amount Q when the accumulation amount Q of the secondary battery (100) is changed. The secondary battery system (6) detects the state of the secondary battery system (6) by using the dV/dQ value.