Secondary Battery Durability Evaluation Using AC Frequency Targeting
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Solution Overview
Problem
Existing durability tests for secondary batteries require a long time to cause deterioration in each part of the battery, making it inefficient for evaluating specific battery reactions.
Innovation Solution
A durability evaluation method for secondary batteries involves applying an alternating current voltage of a specific durability frequency to the battery, adjusting its temperature and state of charge, and evaluating the durability of associated battery reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional durability tests (high temperature holding test, cycle test) are used to evaluate battery deterioration, then comprehensive deterioration factors can be assessed, but the test time becomes excessively long (e.g., one month)
Solution Approach 1:
The patent applies periodic alternating current voltage at specific frequencies to accelerate battery deterioration. By using AC voltage that periodically reverses direction, the method targets specific battery reactions (such as solid electrolyte interface film formation or lithium plating) and accelerates their degradation much faster than conventional DC holding tests, reducing test time from one month to just a few days while maintaining evaluation reliability
Solution Approach 2:
The patent changes key test parameters by applying AC voltage at specifically selected frequencies (e.g., 0.1 Hz, 1 Hz, 10 Hz) rather than using constant DC voltage. This parameter change allows selective acceleration of different battery reactions based on their characteristic time constants, enabling targeted durability evaluation of specific reactions without requiring extremely long test durations
2Productivity
If high frequency AC voltage is applied to accelerate battery reactions, then test efficiency improves, but only fast reactions are affected while slower reactions remain unevaluated
Solution Approach 1:
The patent segments the battery's various reactions by applying AC voltage at multiple different frequencies in separate test stages. Each frequency targets reactions with specific time constants (fast reactions at high frequency, slow reactions at low frequency). This segmentation allows comprehensive evaluation of all reaction types without requiring one extremely long test, as each frequency regime efficiently evaluates its corresponding reaction category
Solution Approach 2:
The patent dynamically adjusts the AC voltage frequency during the durability test based on which battery reactions need acceleration. The test protocol can switch between different frequencies (e.g., starting with high frequency for fast reactions, then switching to low frequency for slow reactions) to adaptively target different deterioration mechanisms, thereby maintaining high test efficiency while covering all reaction types
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 method allows for efficient and appropriate evaluation of the durability of specific battery reactions, reducing the time required for testing and providing insights into battery deterioration mechanisms.
Implementation Method 1
a battery reaction in which time required for the battery reaction is approximately the same as 1/2 cycle of the applied alternating current voltage... can be caused within the period when the alternating current voltage is positive or negative
Data Source
AI summary
A durability evaluation method of a secondary battery includes a durability step of continuing to apply an alternating current voltage of a durability frequency to a first secondary battery for evaluation over a durability test period, and an evaluation step of evaluating durability of an associated battery reaction associated with the durability frequency from among battery reactions of the first secondary battery. A temperature and a state of charge of the first secondary battery are adjusted to a first temperature and a first state of charge, respectively.