Li-Ion Battery Charging Control via Dynamic Power Adjustment
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Solution Overview
Problem
Lithium-ion batteries face durability issues due to lithium deposition during charging, particularly in cold temperatures, which can lead to internal short-circuits and reduced battery life, as existing charging strategies may not adequately prevent the negative electrode from falling below the lithium deposition potential for extended periods.
Innovation Solution
A method that adjusts the charging power and voltage in stages when the battery temperature is low, ensuring the negative electrode's potential only briefly drops below the lithium deposition potential, using a multi-step charging strategy with abrupt power decreases to prevent lithium metal deposition and promote its dissolution back into the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high charging power is applied to reduce charging time, then charging speed is improved, but lithium deposition occurs at the negative electrode leading to internal short circuits and reduced battery life
Solution Approach 1:
The patent implements dynamic adjustment of charging power based on real-time monitoring of negative electrode potential. The charging power is not fixed but continuously adapted to maintain the potential above the lithium deposition threshold, allowing high power charging when safe and reducing power when approaching dangerous levels.
Solution Approach 2:
The system uses feedback control by continuously measuring the negative electrode potential (or calculating it from cell voltage and state of charge) and adjusting the charging power accordingly. When the potential approaches the lithium deposition potential, the charging power is reduced to prevent deposition, creating a closed-loop control system.
2Reliability
If charging power is limited to prevent lithium deposition, then battery safety is improved, but charging time increases significantly
Solution Approach 1:
The charging power is dynamically adjusted rather than statically limited. The system allows high power charging when the negative electrode potential is sufficiently above the deposition threshold, and only reduces power when the potential approaches the critical level, optimizing the balance between speed and safety.
Solution Approach 2:
The patent changes the charging power parameter based on the negative electrode potential parameter. By monitoring potential and adjusting power accordingly, the system transitions between different charging power levels to prevent lithium deposition while maximizing charging speed when conditions permit.
3Productivity
If constant voltage charging is used to optimize charging time, then charging efficiency is improved, but the negative electrode potential remains below lithium deposition potential for extended periods causing lithium metal deposition
Solution Approach 1:
The system introduces feedback control by continuously monitoring the negative electrode potential during constant voltage charging and adjusting the charging current or voltage when the potential approaches the lithium deposition threshold, preventing harmful deposition while maintaining efficient charging.
Solution Approach 2:
The patent transforms static constant voltage charging into a dynamic charging process where the voltage or current is continuously adjusted based on the negative electrode potential, allowing the system to adapt to changing battery conditions and prevent lithium deposition.
4Reliability
If multi-step charging with abrupt power decreases is applied to prevent lithium deposition, then battery durability is improved, but charging time increases due to repeated power reductions
Solution Approach 1:
The patent implements continuous dynamic adjustment of charging power based on real-time negative electrode potential monitoring, replacing multi-step charging with smooth, continuous power modulation. This eliminates abrupt power reductions while maintaining protection against lithium deposition through continuous adaptation to battery conditions.
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 limits lithium metal production, enhancing battery durability by preventing internal short-circuits and maintaining the lithium in its ionic state, while optimizing charging efficiency without excessive degradation.
Implementation Method 1
C6 + Li+ + e- → LiC6, which is the desired reaction of lithium intercalation into carbon
Implementation Method 2
Li+ + e- → Li(m), which is the undesired reaction of Lithium metal deposition
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The invention concerns a method for managing the charging of a Lithium-ion battery, comprising the steps of receiving (101) a measured temperature value of the battery, comparing (103) the measured value received in step a) with a predefined threshold temperature value, generating (104, 104') a control signal to charge said battery, the control signal being generated such that, when the measured temperature value is less than or equal to the threshold temperature value, the charging power, charging voltage or charging intensity decreases in steps, the shift from one step to the next being triggered when a defined voltage value at the battery terminals is reached, and transmitting (105) the control signal to a charger.