Power Battery Decommissioning Index for Individual Aging Assessment
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Solution Overview
Problem
Current methods for decommissioning lithium ion batteries lack standardization and accuracy, relying on a single feature like 80% State of Health (SOH) which fails to account for varying degradation characteristics, leading to unsafe usage and underutilization.
Innovation Solution
A method and system that comprehensively evaluate battery aging using two indicators: SOH and capacity degradation gradient, calculating a decommissioning index (IoD) by dividing the capacity degradation gradient by the square of SOH, with a threshold set based on gamma distribution of decommissioning indexes, allowing for individualized and safe battery decommissioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the traditional decommissioning standard of 80% SOH is used, then the decommissioning process is simple to implement, but it cannot accurately reflect the actual aging state and degradation characteristics of different batteries, leading to unsafe usage or underutilization
Solution Approach 1:
The patent introduces a new decommissioning evaluation index that combines SOH with capacity degradation gradient, transforming the single-parameter evaluation into a multi-parameter composite index. This allows the system to capture both the current health state and the rate of degradation, providing a more accurate and dynamic assessment of battery aging without requiring complex additional hardware
Solution Approach 2:
The patent replaces the need for complex physical testing and characterization systems with a computational approach. By using existing monitoring data (voltage, current, temperature) to calculate SOH and capacity degradation gradient through mathematical models, the system achieves accurate decommissioning evaluation without requiring additional mechanical testing equipment or invasive measurements
2Measurement precision
If comprehensive battery testing and characterization methods are used (as in CN115166563A), then the decommissioning evaluation accuracy is improved, but the process becomes time-consuming and energy-wasting, making large-scale battery decommissioning difficult
Solution Approach 1:
The patent performs preliminary calculations of SOH and capacity degradation gradient during the battery's operational life using continuously monitored data. This allows the decommissioning evaluation to be ready in advance without requiring time-consuming testing at the moment of decommissioning. The evaluation index is updated incrementally as new operational data becomes available
Solution Approach 2:
The patent extracts only the essential information needed for decommissioning evaluation (SOH and capacity degradation gradient) from the vast amount of operational data generated by the battery. By focusing on these two key parameters and using mathematical models to derive the evaluation index, the system avoids the need for comprehensive physical testing while maintaining high accuracy
3Adaptability or versatility
If a single decommissioning threshold (80% SOH) is applied to all batteries, then the evaluation method is simple and uniform, but it fails to account for individual degradation characteristics, resulting in either premature decommissioning or continued unsafe usage
Solution Approach 1:
The patent transforms the static decommissioning threshold into a dynamic evaluation index that adapts to each battery's individual degradation characteristics. The capacity degradation gradient component of the index captures the rate of change in battery health, allowing the evaluation to respond dynamically to each battery's unique aging pattern. This enables accurate identification of decommissioning points tailored to each battery's actual condition
Solution Approach 2:
The patent applies the principle of local quality by allowing each battery to have its own decommissioning evaluation based on its specific operational history and degradation pattern. Rather than imposing a uniform threshold, the system calculates individualized evaluation indexes for each battery based on its unique SOH trajectory and capacity degradation characteristics, enabling precise, battery-specific decommissioning decisions
Data Source
AI summary
A method for standardizing a decommissioning definition of power batteries, including: obtaining power battery capacity data and SOH data; obtaining capacity degradation gradient by subtracting battery capacity of current charge-discharge cycle by battery capacity of previous charge-discharge cycle, and obtaining index of decommissioning (IoD) of power battery by dividing capacity degradation gradient by a square of SOH of current charge-discharge cycle; and when IoD is less than a set threshold, dismantling, disassembling and separating the power battery; otherwise, continuing to use the power battery. An aging state of battery is evaluated comprehensively based on two indexes—the SOH and the capacity degradation gradient, so that a new IoD of the battery is proposed. Each cell can be comprehensively evaluated according to various real-time states of battery, thereby achieving individual decommissioning, which ensures safe use of battery and increases the utilization rate of battery.