Lithium-Sulfur Battery SoH Estimation Using Rest-State OCV Drop
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for a method that can quickly and reliably estimate the state of health (SoH) of lithium-sulfur batteries, which is not practically achievable through existing methods due to the unique chemical behavior of lithium-sulfur batteries.
Innovation Solution
The method involves maintaining a fully charged lithium-sulfur battery in a rest state for a specified period, measuring the open circuit voltage (OCV) after a voltage drop occurs, calculating the difference in OCV (ΔOCV) from an initial measurement, and using the magnitude of ΔOCV to estimate the state of health of the battery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the state of health is calculated by completely discharging a buffered battery and measuring electric charge, then the SoH estimation is theoretically accurate, but it is not practical in actual use environments where full discharge is not feasible
Solution Approach 1:
The patent extracts the essential information needed for SoH estimation (voltage characteristics) from a simplified test protocol (rest state voltage measurement after full charge) rather than requiring complete battery discharge. This allows obtaining accurate SoH data without the practical burden of full discharge cycles.
Solution Approach 2:
The patent changes the measurement parameter from total charge capacity (requiring full discharge) to voltage drop characteristics during rest state. By measuring OCV at different time points after full charging and calculating voltage differences, the method achieves SoH estimation through a different physical parameter that is easier to measure in practice.
2Adaptability or versatility
If existing SoH estimation methods are applied to lithium-sulfur batteries, then general battery estimation approaches are used, but they fail to account for the unique chemical behavior of lithium-sulfur batteries
Solution Approach 1:
The patent applies a specialized estimation method tailored specifically to lithium-sulfur battery chemistry rather than using a generic approach. By focusing on the specific voltage characteristics and rest state behavior of Li-S batteries, the method achieves reliable results for this particular battery type.
Solution Approach 2:
The patent performs a full charge operation before the voltage measurement to establish a known initial state. This preliminary action ensures that the battery is in a consistent, reproducible state (fully charged rest state) before measuring the voltage drop, which is essential for accurate SoH estimation in lithium-sulfur batteries with their unique chemical behavior.
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 a simple, quick, and reliable estimation of the state of health of lithium-sulfur batteries, enabling better battery management and improving the efficiency, reliability, and safety of the batteries.
Implementation Method 1
The sulfur at the cathode of the lithium-sulfur battery is reduced in two steps when the lithium-sulfur battery is discharged. In a first step, sulfur (e.g., the elemental sulfur) is reduced to lithium polysulfide (Li 2 S 8, Li 2 S 6, Li 2 S 5, or Li 2 S 4).
Implementation Method 2
maintaining a battery, which is fully charged and for which a SoH is to be confirmed, in a rest state for 0.01 seconds or more in a state in which the battery (for which the SoH is to be confirmed) is fully charged; measuring OCV (det) in a state in which a voltage drop is made during the rest state
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention provides a method of estimating a state of health (SoH) of a lithium-sulfur battery, including the steps of: a) maintaining a state of health confirmation target battery in a rest state for 0.01 seconds or more in a state in which the state of health confirmation target battery is fully charged; b) measuring OCV(det) in a state in which a voltage drop is made during the rest state; c) calculating ΔOCV by subtracting OCV(det) from OCV(ini) previously measured in the same manner as in steps a) and b) at an initial stage of use of the state of health confirmation target battery; and d) estimating a state of health (%) of the battery from a magnitude of the ΔOCV.