Lithium-Sulfur Battery SOC Detection from Early and Late Voltage Drops
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Solution Overview
Problem
Existing methods for determining the remaining capacity of lithium-sulfur batteries are complex and lack sufficient precision, especially when the capacity is 70% or less.
Innovation Solution
A method involving the measurement of initial and late voltage drop values after applying a constant current, with subsequent calculations to determine the remaining capacity using specific equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods (complex modeling, optical monitoring) are used to determine remaining capacity, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential voltage drop measurements at two specific time points (initial and late) after constant current application, discarding the need for complex modeling or optical monitoring systems. This selective extraction of critical measurement parameters achieves sufficient precision while dramatically simplifying the determination method.
Solution Approach 2:
Instead of using complex models to infer remaining capacity from multiple parameters, the patent inverts the approach by using simple voltage drop measurements combined with empirical equations (Eq. 1 and Eq. 2) to directly calculate remaining capacity, achieving precision through mathematical transformation rather than complex physical modeling.
2Ease of operation
If voltage measurement only is used to determine remaining capacity, then ease of operation is improved, but measurement precision deteriorates when remaining capacity is 70% or less
Solution Approach 1:
The patent applies a constant current pulse before the actual voltage measurement to induce a measurable voltage drop. This preliminary action creates a distinct initial voltage drop (dV1) and late voltage drop (dV2) that can be measured and used in the calculation equations, enabling precise remaining capacity determination at low SOC levels while maintaining operational simplicity.
Solution Approach 2:
The patent changes the measurement parameter from static open-circuit voltage to dynamic voltage drop under constant current loading. By measuring voltage drops at two different time points (initial and late) after current application, the method captures electrochemical state information that correlates with remaining capacity, especially in the 70% or less range where traditional voltage measurement fails.
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 reliable and accurate determination of the remaining capacity of lithium-sulfur batteries, even at 70% or less, in a simple manner.
Implementation Method 1
measuring the initial voltage drop value dV1 at any one point in the range of 0.01 to 0.3 sec after applying a constant current to the battery
Data Source
AI summary
The present disclosure provides a method for determining the remaining capacity of a lithium-sulfur battery using a voltage drop value obtained by applying a constant current in an open-circuit state and a battery pack implementing the method.