Li-Ion Charging Current Threshold Control for Lithium Plating
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Solution Overview
Problem
Existing lithium ion battery charging methods fail to sufficiently suppress lithium metal precipitation, especially when using chargers with low performance, leading to potential short-circuits.
Innovation Solution
A charging method that determines two threshold values for the charging current: a first threshold value at which lithium metal precipitation is likely to occur, and a second threshold value at which precipitation is always suppressed. The method controls the charging current using the difference between these threshold values to prevent excessive lithium metal precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charging current is lowered after the terminal voltage reaches the Li precipitation start voltage, then the Li precipitation is suppressed, but the charging time increases and charging efficiency decreases
Solution Approach 1:
The patent applies preliminary action by predicting the Li precipitation start voltage in advance using an equivalent circuit model and open-circuit voltage information before it actually occurs. This allows the charging current to be reduced proactively, preventing Li precipitation while maintaining efficient charging. The controller calculates the predicted Li precipitation start voltage and compares it with the actual terminal voltage to determine when to adjust charging current, rather than waiting for Li precipitation to actually occur.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the terminal voltage, charging current, and open-circuit voltage, and using this information to dynamically adjust the charging current. The equivalent circuit model provides real-time prediction of Li precipitation risk, and the controller adjusts charging parameters based on this feedback to prevent Li precipitation while optimizing charging efficiency.
2Device complexity
If the charging current control response is slow due to low charger performance, then the charger is simpler and cheaper, but lithium metal precipitation occurs because the current decrease is delayed
Solution Approach 1:
The patent applies preliminary action by predicting the Li precipitation start voltage in advance using an equivalent circuit model and open-circuit voltage information before it actually occurs. This allows the charging current to be reduced proactively, preventing Li precipitation even with slow-responding chargers. The controller calculates the predicted Li precipitation start voltage and compares it with the actual terminal voltage to determine when to adjust charging current, rather than waiting for Li precipitation to actually occur.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the terminal voltage, charging current, and open-circuit voltage, and using this information to dynamically adjust the charging current. The equivalent circuit model provides real-time prediction of Li precipitation risk, and the controller adjusts charging parameters based on this feedback to prevent Li precipitation while optimizing charging efficiency.
3Productivity
If the first charging current or first charging power is increased to improve charging speed, then the charging efficiency increases, but the Li precipitation start voltage decreases making precipitation more likely
Solution Approach 1:
The patent applies preliminary action by predicting the Li precipitation start voltage in advance using an equivalent circuit model and open-circuit voltage information before it actually occurs. This allows the charging current to be reduced proactively, preventing Li precipitation even when high charging currents are applied. The controller calculates the predicted Li precipitation start voltage and compares it with the actual terminal voltage to determine when to adjust charging current, rather than waiting for Li precipitation to actually occur.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the terminal voltage, charging current, and open-circuit voltage, and using this information to dynamically adjust the charging current. The equivalent circuit model provides real-time prediction of Li precipitation risk, and the controller adjusts charging parameters based on this feedback to prevent Li precipitation while optimizing charging efficiency.
Data Source
AI summary
A charging method includes: determining, for charging current of a lithium ion battery, first and a second threshold values each representing a current boundary value at which precipitation of lithium metal becomes likely to occur on an electrode of the lithium ion battery; and controlling the charging current of the lithium ion battery using a difference between the first and second threshold values, and the second threshold value. The first threshold value represents a current boundary value at which precipitation of the lithium metal becomes likely to occur when the charging current of the lithium ion battery exceeds the first threshold value. The second threshold value is 10 smaller than the first threshold value, and represents a current boundary value at which precipitation of the lithium metal becomes likely to occur when the charging current of the lithium ion battery continuously exceeds the second threshold value.