Battery SOC Assessment Using Entropy and Enthalpy Monitoring

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Solution Overview

Problem

Current methods for determining the state of charge (SOC) of electrochemical cells, particularly alkaline and dry Zn/MnO2 batteries, are unreliable and lack universality, as they are empirical and do not apply to all battery types, making it difficult to predict remaining capacity and battery end of service.

Innovation Solution

A method that assesses SOC/SOD by measuring entropy (ΔS) and enthalpy (ΔH) during charge, discharge, and rest modes, using the equations SOC=α+βΔS+γΔH and SOD=100%−SOC, with parameters α, β, and γ depending on chemical data and state of health (SOH), and implementing this with an integrated circuit for online monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If empirical methods (Coulomb counting, Kalman filter, neural network) are used to determine SOC, then the determination can be performed with simple measurements, but the methods are not universal and do not apply to all battery types

Engineering Contradiction:

Improveuniversality of SOC determination methodVSAvoidaccuracy of SOC determination

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameters from electrical quantities (current, voltage) to thermodynamic quantities (entropy, enthalpy) that are fundamental to the electrochemical reactions occurring in the battery. This allows the same thermodynamic principles to apply universally across different battery chemistries while maintaining high measurement precision through the direct relationship between thermodynamic parameters and state of charge

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent substitutes electrical measurement systems (Coulomb counting, voltage-based methods) with thermodynamic measurement systems that measure entropy and enthalpy changes. This substitution enables universal applicability because thermodynamic laws are chemistry-independent, while the measurements remain precise through direct correlation with the electrochemical state

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If thermodynamic measurements (entropy and enthalpy) are used to assess SOC/SOD, then accurate assessment is achieved with high accuracy (>97%), but the measurement and calculation complexity increases

Engineering Contradiction:

Improveaccuracy of SOC/SOD assessmentVSAvoidcomplexity of measurement and calculation system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary computational layer that processes temperature, voltage, and current measurements to calculate entropy and enthalpy changes. This intermediary system translates complex thermodynamic concepts into practical measurements using standard sensor data, thereby achieving high accuracy without requiring complex dedicated measurement hardware

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent enables the battery management system to self-determine SOC/SOD by using measurements taken during normal battery operation (temperature, voltage, current). The system serves itself by utilizing its own operational data to assess its state, eliminating the need for external complex measurement equipment while maintaining >97% accuracy

Inventive Principle:

Principle #25Self-service

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 approach provides accurate SOC/SOD assessment for various battery types, including primary and rechargeable cells, with high accuracy (>97%) and can be implemented online using temperature, current, and voltage probes, enabling reliable prediction of battery capacity and health.

Implementation Method 1

measuring entropy (ΔS) and enthalpy (ΔH) for the electrochemical cell, in the course of the first and second operational modes and during rest

Methodology Applied

Scientific EffectEntropy measurement:

Implementation Method 2

measuring entropy (ΔS) and enthalpy (ΔH) for the electrochemical cell, in the course of the first and second operational modes and during rest

Methodology Applied

Scientific EffectEnthalpy measurement:

Implementation Method 3

Entropy and enthalpy are determined by the temperature dependence of open-circuit voltage (OCV) at each SOC

Methodology Applied

Scientific EffectOpen-circuit voltage temperature dependence:

Data Source

PatentUS11901517B2Method and system for assessing a state of charge/discharge (SOC/SOD) for an electrochemical cell

Publication Date: 2024.02.13 YAZAMI IP PTE LTD

AI summary

A method for assessing a state of charge/discharge (SOC/SOD) for a secondary electrochemical cell, the cell having a first operational mode during which the cell is charged from a power supply connected to terminals of the cell, a second operational mode during which the cell is discharged into a load and a rest mode, the method comprising steps of measuring entropy and enthalpy for the electrochemical cell in the course of the first and second operational modes and during rest, and calculating a data representative of the state of charge/discharge (SOC/SOD).