Battery Salt Concentration Monitoring via Electrolyte Flow

Solution Overview

Problem

Existing battery systems fail to directly measure and understand deviations in salt concentration in electrolytes, relying on indirect methods that do not account for the underlying factors causing these deviations, which can lead to increased internal resistance values.

Innovation Solution

A battery system that includes a secondary battery, a temperature sensor, and a controller to calculate the deviation in salt concentration by determining the flow velocities of the electrolyte using equations that account for density changes with temperature, allowing for direct measurement of salt concentration distribution and resistance increase.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If indirect measurement methods are used to detect salt concentration deviation, then the measurement complexity is reduced, but the measurement precision deteriorates

Engineering Contradiction:

Improvemeasurement complexityVSAvoidsalt concentration measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect electrical measurement methods with direct optical measurement using a spectrometer. The spectrometer measures the absorbance spectrum of the electrolyte solution, and salt concentration is calculated from the spectral data using the relationship between absorbance and ion concentration. This substitution of measurement principle achieves both direct observation and high precision without complex mechanical intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary substance (indicator dye) that changes its optical properties in response to salt concentration changes. The spectrometer detects these optical changes, and the controller calculates the actual salt concentration based on the spectral data. This intermediary approach enables precise measurement while keeping the measurement system relatively simple.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If battery resistance increase rate is calculated using current density ratio, then the internal resistance monitoring is simplified, but the reliability of salt concentration detection deteriorates

Engineering Contradiction:

Improveinternal resistance monitoring complexityVSAvoidsalt concentration detection reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces an intermediary substance (indicator dye) that changes its optical properties in response to salt concentration changes. The spectrometer detects these optical changes, and the controller calculates the actual salt concentration based on the spectral data. This intermediary approach enables precise measurement while keeping the measurement system relatively simple.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces indirect electrical measurement methods with direct optical measurement using a spectrometer. The spectrometer measures the absorbance spectrum of the electrolyte solution, and salt concentration is calculated from the spectral data using the relationship between absorbance and ion concentration. This substitution of measurement principle achieves both direct observation and high precision without complex mechanical intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If temperature effects on electrolyte density are not considered, then the calculation process is simplified, but the accuracy of salt concentration distribution calculation deteriorates

Engineering Contradiction:

Improvecalculation process complexityVSAvoidsalt concentration distribution accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent dynamically adjusts the electrolyte density parameter in the convection-diffusion equation based on the measured battery temperature. The controller retrieves temperature data from a temperature sensor, calculates the corresponding electrolyte density, and uses this temperature-dependent density value in the salt concentration distribution calculation. This parameter adaptation ensures accurate calculations across varying operating conditions without overly complicating the system.

Inventive Principle:

Principle #35Parameter changes

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 enables accurate calculation of salt concentration distribution and resistance increase, allowing for effective management of battery performance and longevity by directly addressing the root cause of internal resistance issues.

Implementation Method 1

The temperature sensor is configured to specify a temperature of the secondary battery

Methodology Applied

Scientific EffectTemperature detection:

Implementation Method 2

The first flow velocity is a flow velocity when the electrolyte flows from an inside of the power generation element toward an outside of the power generation element. The second flow velocity is a flow velocity when the electrolyte flows from the outside of the power generation element toward the inside of the power generation element

Methodology Applied

Scientific EffectThermal convection: Convection

Implementation Method 3

The density changes according to the temperature of the secondary battery

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 4

The controller is configured to calculate a salt concentration distribution in the power generation element based on the first flow velocity and the second flow velocity

Methodology Applied

Scientific EffectConvection-diffusion: Convection

Data Source

PatentUS10594003B2Battery system

Publication Date: 2020.03.17 TOYOTA JIDOSHA KK

AI summary

A battery system according includes a secondary battery, a temperature sensor and a controller. The secondary battery includes a power generation element configured to perform charging and discharging, an electrolyte, and a battery case. The electrolyte is impregnated inside the power generation element. The power generation element and the electrolyte is housed in the battery case. The temperature sensor is configured to specify a temperature of the secondary battery. The controller is configured to calculate a deviation in salt concentration in the electrolyte. The controller is configured to calculate a first flow velocity and a second flow velocity at each position in the power generation element in the flow direction of the electrolyte using an equation defining a flow of the electrolyte. The first flow velocity is a flow velocity when the electrolyte flows from an inside of the power generation element toward an outside of the power generation element. The second flow velocity is a flow velocity when the electrolyte flows from the outside of the power generation element toward the inside of the power generation element. The equation includes, as a parameter, a density of the electrolyte. The density is specified from the temperature. The density changes according to the temperature of the secondary battery. The controller is configured to calculate a salt concentration distribution in the power generation element based on the first flow velocity and the second flow velocity.