Battery SOH Assessment via Thermodynamic Entropy and Enthalpy
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Solution Overview
Problem
Current methods for assessing the state of health (SOH) of batteries are not practical for real-time evaluation and lack accuracy, as they require full charging and discharging cycles, which is not feasible for continuous monitoring.
Innovation Solution
A method and system that utilize thermodynamic data, specifically entropy and enthalpy variations, to estimate the SOH of electrochemical cells, employing an entropy-revealer tool that implements machine-learning models and pattern recognition algorithms to analyze open-circuit voltage and thermodynamic profiles for accurate SOH assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full charging and discharging cycles are used to assess SOH, then measurement accuracy is improved, but productivity deteriorates due to inability to perform real-time assessment
Solution Approach 1:
The patent extracts the essential thermodynamic information needed for SOH assessment from the complete charging-discharging cycle. By measuring entropy and enthalpy variations at specific state of charge points (using dU/dT measurements at open circuit voltage), the method obtains sufficient data to calculate SOH without requiring full cycle completion, thus enabling real-time assessment while maintaining accuracy.
Solution Approach 2:
The patent applies partial action by performing measurements at selected state of charge points rather than requiring complete charging and discharging cycles. The method measures thermodynamic parameters at specific SOC levels (e.g., 0%, 50%, 100%) to obtain entropy and enthalpy variations, which are sufficient for SOH calculation, thereby reducing the time and operational requirements while maintaining assessment accuracy.
2Ease of operation
If traditional SOH assessment methods are used, then ease of operation is improved through simple capacity ratio calculation, but measurement precision deteriorates due to inability to capture battery degradation accurately
Solution Approach 1:
The patent replaces the simple capacity ratio calculation method with a thermodynamic measurement approach. Instead of merely comparing charge/discharge capacities, the method uses entropy and enthalpy variations derived from temperature-dependent voltage measurements (dU/dT) to assess SOH. This substitution provides more accurate degradation detection while maintaining operational simplicity through automated thermodynamic calculations.
Solution Approach 2:
The patent changes the measurement parameters from simple capacity values to thermodynamic parameters (entropy S and enthalpy H variations). By measuring dU/dT at different temperatures and state of charge levels, the method obtains entropy and enthalpy data that are more sensitive to battery degradation mechanisms, thereby improving measurement precision while maintaining ease of operation through systematic parameter measurement.
3Measurement precision
If thermodynamic measurements are performed, then measurement precision is improved for SOH assessment, but device complexity increases due to additional sensors and measurement systems
Solution Approach 1:
The patent achieves multi-functionality by using the existing battery management system temperature sensors and voltage measurements to perform multiple functions: standard battery monitoring, state of charge estimation, and thermodynamic parameter calculation for SOH assessment. The same temperature and voltage data used for basic battery management are additionally processed to derive dU/dT, entropy, and enthalpy variations, eliminating the need for separate dedicated measurement systems.
Solution Approach 2:
The method enables the battery management system to self-assess SOH using its own existing measurement capabilities. The BMS's voltage and temperature sensors, already present for standard battery monitoring, are utilized to perform thermodynamic measurements and calculate SOH without requiring external dedicated equipment. The system serves itself by processing its own operational data for advanced diagnostics.
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
Enables online, accurate, and real-time assessment of battery SOH, allowing for improved battery management, safety, and performance prediction, even for unknown battery chemistries, by establishing relationships between thermodynamic data and SOH through machine-learning models.
Implementation Method 1
estimating said state of health (SOH) of said electrochemical cell from thermodynamics data related to said cell, said thermodynamics data including entropy and enthalpy variations ΔS, ΔH within said cell
Implementation Method 2
carrying out measurements of a number of cell parameters, including open circuit voltage, time and temperature
Data Source
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AI summary
A method for online assessing a state of health (SOH) of an electrochemical cell, comprises a step for estimating said state of health (SOH) of said electrochemical cell from thermodynamics data related to said cell, said thermodynamics data including entropy and enthalpy variations ΔS, ΔΗ within said cell. A system for fast-charging a rechargeable battery with terminals connected to internal electrochemical cells, comprises a power supply connected to said rechargeable battery and arranged for applying a time-varying charging voltage to said battery terminals, a charging- control processor for controlling said power supply, and a system for online assessing a state of health (SOH) of said battery, said SOH assessment system comprising means for estimating said state of health (SOH) of said electrochemical cell from thermodynamics data related to said battery.