Li-Ion Charging Control Using Side Reaction Rate Estimation
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Solution Overview
Problem
Current charging methods for lithium-ion batteries fail to simultaneously reduce charging time and suppress degradation speed, leading to increased heat generation and reduced battery lifespan.
Innovation Solution
A charging apparatus and method that quantitatively estimates the side reaction rate in lithium-ion batteries during charging, using a predefined electrochemical reduced order model (ROM) to adjust the charging current and control the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high power chargers (DC fast charging, super charger, extreme fast charging) are used to reduce charging time, then charging time is reduced, but degradation speed increases and heat generation increases
Solution Approach 1:
The charging method dynamically adjusts charging current based on real-time monitoring of voltage, temperature, and state of charge. The control unit modifies charging parameters during the charging process to optimize both charging speed and battery safety, transitioning from static high-power charging to adaptive dynamic charging that responds to battery conditions.
Solution Approach 2:
The system implements feedback control by continuously measuring voltage, temperature, and charge state, then using this information to adjust charging current. The control unit receives real-time data from sensors and modifies charging parameters accordingly, creating a closed-loop system that balances charging speed with battery protection.
2Loss of time
If constant current (CC) charging method is used to reduce charging time, then charging time is reduced, but overcharging occurs and temperature rise increases
Solution Approach 1:
The system uses feedback control by continuously monitoring voltage and temperature during charging. When voltage approaches cutoff levels or temperature rises, the control unit automatically reduces charging current, preventing overcharging and excessive heat generation while maintaining efficient charging throughout the process.
Solution Approach 2:
The charging method changes operational parameters dynamically based on battery state. It transitions from constant current charging to variable current charging by adjusting the magnitude of charging current according to real-time measurements of voltage, temperature, and state of charge, optimizing charging efficiency while preventing harmful effects.
3Reliability
If constant voltage (CV) charging method is used to prevent overcharging, then overcharging is prevented, but charging time increases due to low charging current at high SOC
Solution Approach 1:
The system dynamically adjusts charging current based on battery state of charge and temperature conditions. Rather than using fixed constant voltage charging, the control unit modulates current magnitude during charging to maintain optimal charging speed while preventing overcharge, achieving both safety and time efficiency.
Solution Approach 2:
The method changes charging parameters adaptively by modifying current magnitude based on real-time battery conditions. This allows the system to maintain higher charging currents longer into the charging cycle compared to traditional CV methods, reducing overall charging time while still preventing overcharge through continuous monitoring and adjustment.
Data Source
AI summary
A charging apparatus includes a control unit configured to determine an average ion concentration, a surface ion concentration and a solid phase potential for anode particles and an electrolyte potential in an anode, using a predefined electrochemical reduced order model. The control unit is further configured to determine a side reaction rate from the solid phase potential and the electrolyte potential. The control unit is further configured to reduce the magnitude of the charging current applied to a secondary battery based on at least one of a cutoff voltage, the surface ion concentration and the side reaction rate.