Secondary Cell Electrolyte Loss Estimation via Voltage and Temperature

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Solution Overview

Problem

Existing methods fail to accurately estimate the amount of electrolyte solution decrease in secondary cells with high aspect ratio electrode assemblies, where gas generated by electrolyte decomposition tends to remain, leading to inaccurate estimation of electrolyte loss.

Innovation Solution

A power supply device with a detection system for voltage and temperature, coupled with storage of correlation data from cycle and storage tests, calculates indices to accurately estimate electrolyte solution decrease during energization and storage, enabling precise monitoring and alerting or power management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gas detection method is used to estimate electrolyte decomposition, then estimation can be performed, but estimation accuracy deteriorates in secondary cells with high aspect ratio electrode assemblies where gas remains trapped

Engineering Contradiction:

Improveestimation accuracy of electrolyte decompositionVSAvoidapplicability to various secondary cell types

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The invention changes the estimation parameters from gas amount to voltage and temperature, which are measurable parameters that reflect electrolyte decomposition without being affected by gas trapping issues in high aspect ratio cells

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces voltage and temperature as intermediary parameters that indirectly indicate electrolyte decomposition, avoiding the direct measurement problem of trapped gas in high aspect ratio electrode assemblies

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If single estimation method is used for both energization and storage, then device complexity is reduced, but estimation accuracy deteriorates because decomposition characteristics differ between states

Engineering Contradiction:

Improveestimation accuracy of electrolyte decompositionVSAvoidcomplexity of estimation system

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The invention segments the estimation process into two distinct methods: one for energization state using voltage change rate, and another for storage state using temperature and voltage relationships, improving accuracy for each specific state

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention dynamically selects the appropriate estimation method based on the current state (energization or storage) of the secondary cell, adapting the estimation approach to match the operational conditions

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20230395891A1Power supply device

Publication Date: 2023.12.07 TOYOTA JIDOSHA KK

AI summary

A power supply device includes a secondary cell, a detection device, a storage device, and a control device. The secondary cell includes an electrolyte solution. The detection device detects the voltage and temperature of the secondary cell. The storage device stores first information and second information. The first information indicates the relationship among the voltage, the temperature, and the amount of decrease in the electrolyte solution during energization of the secondary cell. The second information indicates the relationship among the voltage, the temperature, and the amount of decrease in the electrolyte solution during storage of the secondary cell. The control device calculates a first index indicating the amount of decrease in the electrolyte solution.