Negative Electrode Potential Control in Traction Battery Charging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium precipitation during the charging of traction batteries can reduce performance, cycle life, and pose safety risks such as combustion and explosion, necessitating improved safety performance in battery technologies.
Innovation Solution
A method and battery management system that monitor and control the discharge of traction batteries by setting a safety threshold for the negative electrode potential, preventing lithium precipitation by discharging the battery before it reaches a critical potential, and dynamically adjusting discharging parameters to balance charging efficiency and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current is increased to improve charging efficiency, then the charging speed increases, but lithium precipitation occurs on the negative electrode which reduces safety and battery life
Solution Approach 1:
The BMS performs preliminary action by detecting the negative electrode potential before lithium precipitation occurs and proactively controlling the battery to discharge. This preventive approach stops the charging process before the harmful lithium deposition can form, resolving the contradiction between charging efficiency and safety by acting in advance rather than waiting for failure conditions.
Solution Approach 2:
The system implements feedback control by continuously monitoring the negative electrode potential during charging and using this information to dynamically adjust the charging current. When the potential approaches the critical threshold, the BMS reduces or reverses the current to prevent lithium precipitation, thereby maintaining both high charging efficiency and safety performance through real-time adjustment.
2Reliability
If the negative electrode potential is monitored continuously to prevent lithium precipitation, then the safety performance improves, but the device complexity increases due to additional monitoring and control requirements
Solution Approach 1:
The BMS performs multiple functions using the same monitoring infrastructure: it tracks negative electrode potential for safety purposes, uses this data to control charging current, and manages overall battery state. By making the monitoring system multi-functional, the patent avoids adding separate dedicated systems while still achieving continuous safety monitoring, thus improving safety without proportionally increasing complexity.
3Reliability
If the battery is controlled to discharge when approaching critical potential, then lithium precipitation is prevented, but the charging time increases due to intermittent discharging cycles
Solution Approach 1:
The system applies partial action by controlling the battery to discharge only for the minimum necessary duration and magnitude required to prevent lithium precipitation. Rather than complete discharge cycles, the BMS applies just enough reverse current to maintain the negative electrode potential above the critical threshold, then resumes charging. This partial approach prevents the harmful effect while minimizing the time loss.
Data Source
AI summary
Embodiments of the present application provide a method for charging a traction battery and a battery management system, where the method includes: obtaining a negative electrode potential of a traction battery during a charging process of the traction battery; and controlling the traction battery to be discharged when a difference between the negative electrode potential and a preset potential is less than or equal to a safety threshold. The method and the battery management system in the embodiments of the present application can improve the safety performance of the traction battery.