Battery Diffusion Modeling for Salt Precipitation Detection
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Solution Overview
Problem
Existing battery management systems face challenges in accurately diagnosing lithium-ion battery abnormalities, particularly lithium plating and salt precipitation, which can lead to reduced lifespan and internal short circuits, due to difficulties in modeling lithium ion diffusion at low temperatures and as batteries age.
Innovation Solution
A method and apparatus using an electrochemical model based on a single particle model of a battery's cathode and anode to estimate internal lithium ion concentrations and diagnose salt precipitation by calculating the difference in lithium ion diffusion between the cathode and anode, and estimating overpotential to determine the battery's internal state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrochemical models are used to estimate internal states of batteries, then measurement precision of internal states is improved, but device complexity increases due to the need for sophisticated modeling and calculation
Solution Approach 1:
The battery is segmented into multiple discrete particles representing different regions (core, middle, surface) of cathode and anode materials. Each particle is modeled independently with its own lithium concentration state, allowing the complex continuous diffusion process to be broken down into manageable discrete states that can be estimated separately and then combined to diagnose salt precipitation.
Solution Approach 2:
An electrochemical model acts as an intermediary between measurable battery parameters (voltage, current, temperature) and the unmeasurable internal states (lithium concentration distribution, salt precipitation). The model uses equivalent circuits and electrochemical equations to bridge the gap between external measurements and internal conditions, enabling indirect estimation of internal states without direct sensors.
2Temperature
If diffusion of lithium ions is slowed at low temperatures, then ion conductivity is reduced, but salt precipitation becomes more likely as lithium ions fail to diffuse into anodes
Solution Approach 1:
The system performs preliminary diagnosis of salt precipitation risk by estimating lithium concentration differences between cathode and anode particles before actual precipitation occurs. By continuously monitoring the concentration difference and comparing it against threshold values, the system can predict and prevent salt precipitation by adjusting charging parameters in advance, rather than waiting for the harmful effect to manifest.
Solution Approach 2:
The model incorporates temperature-dependent diffusion coefficients that change with battery temperature. By adjusting the diffusion parameters in the electrochemical model based on measured temperature, the system accurately reflects the reduced lithium ion mobility at low temperatures and uses this information to diagnose salt precipitation risk under varying thermal conditions.
3Duration of action of stationary object
If batteries age, then diffusion of lithium ions is slowed, but salt precipitation issues become more pronounced
Solution Approach 1:
The diagnostic system performs preliminary assessment of salt precipitation risk by estimating the difference between internal lithium concentrations of cathode and anode particles. By continuously monitoring this concentration difference and comparing it to threshold values, the system can predict salt precipitation before it occurs, enabling preventive measures to be taken that protect aged batteries from further degradation.
Solution Approach 2:
The system uses feedback from the electrochemical model to adjust charging strategies based on diagnosed salt precipitation risk. When the model estimates a high concentration difference indicating precipitation risk, the feedback loop triggers adjustments to charging current or voltage to reduce the risk, creating a closed-loop control system that adapts to the battery's aging state and prevents harmful effects.
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 diagnoses battery abnormalities, preventing salt precipitation and reducing the risk of internal short circuits, thereby extending battery life and maintaining performance by accurately modeling lithium ion behavior.
Implementation Method 1
the electrochemical model comprising a model configured to calculate internal lithium ion concentrations of the cathode and the anode by considering a difference in diffusion of lithium ions between the cathode and the anode
Implementation Method 2
calculating a value of an overpotential between the anode and the separator of the battery by using the potential of the electrolyte and the potential of the anode and diagnosing the salt precipitation of the battery based on the value of the overpotential
Data Source
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AI summary
A method of diagnosing battery abnormalities including acquiring at least one parameter of the battery, and determining, based on, salt precipitation of the battery by using an electrochemical model calculated based on a single particle model of a cathode and an anode of the battery, the electrochemical model comprising a model configured to calculate internal lithium ion concentrations of the cathode and the anode by considering a difference in diffusion of lithium ions between the cathode and the anode of the battery and to estimate an internal state of the battery by using a difference between the internal lithium ion concentrations of the cathode and the anode.