Battery Current Limit Estimation for Diffusion-Layer Overvoltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery control systems fail to set appropriate upper limit current values for secondary batteries, particularly in high-current regions where steep changes in battery voltage occur due to ion concentration gradients in the diffusion layer, leading to potential battery deterioration.
Innovation Solution
A battery control apparatus that includes a concentration gradient estimator to calculate the ion concentration gradient and an upper limit current determiner to set the upper limit current value based on this gradient, ensuring the overvoltage remains within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the upper limit current value is increased to improve power output, then productivity is improved, but the ion concentration gradient in the diffusion layer increases causing steep voltage changes and battery deterioration
Solution Approach 1:
The patent applies dynamics by making the upper limit current value variable rather than fixed. The control device dynamically adjusts the upper limit current based on real-time ion concentration gradient estimates, allowing the system to operate at higher currents when conditions permit (improving productivity) while preventing excessive currents that would cause voltage steepness and deterioration (protecting reliability).
Solution Approach 2:
The patent changes the parameter of upper limit current value based on the ion concentration gradient. By continuously monitoring and adjusting this parameter according to the estimated gradient, the system optimizes the balance between power output and battery protection, resolving the contradiction between productivity and reliability.
2Device complexity
If the upper limit current value is set based on fixed thresholds, then device complexity is reduced, but measurement precision of ion concentration effects is insufficient leading to inappropriate current limits
Solution Approach 1:
The patent replaces direct physical measurement of ion concentration gradient with an estimation system based on electrical measurements. The concentration gradient estimation device calculates the gradient indirectly from voltage and current data, avoiding the need for complex physical sensors while achieving precise detection of ion concentration effects.
Solution Approach 2:
The patent introduces an intermediary estimation mechanism that translates easily measurable electrical parameters (voltage, current) into information about the ion concentration gradient. This intermediary approach maintains measurement precision without requiring direct complex measurement of the gradient itself.
3Reliability
If the upper limit current value is reduced to prevent voltage steepness, then battery deterioration is suppressed, but power output and charging/discharging speed decrease
Solution Approach 1:
The system dynamically adjusts the upper limit current based on real-time ion concentration gradient conditions. When the gradient is low (safe conditions), the system allows higher currents for maximum power output. When the gradient increases (risky conditions), the system reduces the current limit to prevent deterioration. This dynamic approach resolves the contradiction between power and durability.
Solution Approach 2:
The upper limit current parameter is continuously adjusted based on the ion concentration gradient estimation. This parameter change strategy allows the system to optimize power output within safe operating boundaries, preventing both excessive current damage and unnecessary power limitation.
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 effectively sets appropriate upper limit current values, preventing steep voltage changes and reducing battery deterioration by considering the ion concentration gradient, thereby maximizing battery performance and longevity.
Implementation Method 1
an ion concentration gradient in a diffusion layer formed around an interface between an electrode and an electrolyte of a secondary battery
Implementation Method 2
an overvoltage of the secondary battery according to the ion concentration gradient
Data Source
AI summary
An appropriate upper limit current value is set in consideration of steep change in battery voltage in a high-current region caused by the ion concentration gradient in a diffusion layer formed around an interface between an electrode and an electrolyte. An upper limit current calculator 152 includes: a concentration gradient estimator 1523 that estimates a lithium ion concentration gradient in a diffusion layer formed around an interface between an electrode and an electrolyte of a battery, based on a current flowing in the battery, or on the current and a temperature; and an upper limit current determiner 1524 that determines an upper limit current value of the battery, based on the lithium ion concentration gradient. The upper limit current determiner 1524 determines the upper limit current value such that an overvoltage of the battery according to the lithium ion concentration gradient falls within a predetermined range.