Battery Charging Profile Using Negative Electrode Surface Potential
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Solution Overview
Problem
Conventional charging profiles for lithium secondary batteries in electric vehicles limit charging time due to the risk of lithium deposition on the negative electrode, which can cause side reactions leading to heating, fires, or explosions, and thus require a conservative reduction in charging current as the battery approaches full charge.
Innovation Solution
A method and system that determine a charging profile based on the negative electrode surface potential, allowing for an increased current rate at the latter stage of charging without lithium deposition by using a test unit cell to establish reference SOC and voltage conditions, and a control unit to manage the charging process, ensuring safe and efficient charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fast charging is done by supplying large currents to batteries, then charging time is reduced, but lithium deposition occurs on the negative electrode surface causing safety risks
Solution Approach 1:
The patent applies dynamics by transitioning from a static, conservative charging profile to a dynamic charging strategy that continuously adjusts the charging current based on real-time negative electrode surface potential measurements. The charging current is dynamically optimized to maintain it below the lithium deposition threshold while maximizing charging speed, thereby resolving the contradiction between fast charging and safety.
Solution Approach 2:
The patent implements feedback by measuring the negative electrode surface potential in real-time during charging and using this information to adjust the charging current. The control system receives feedback from the surface potential measurement and dynamically modifies the charging profile to prevent lithium deposition while enabling faster charging, thus resolving the safety-time contradiction.
2Reliability
If charging current is reduced to prevent lithium deposition, then safety is improved, but charging time increases significantly
Solution Approach 1:
The patent uses feedback from real-time negative electrode surface potential measurements to dynamically adjust the charging current. This allows the system to maintain high charging currents when the surface potential indicates low lithium deposition risk, while reducing current only when necessary, thereby preventing lithium deposition without significantly extending charging time.
Solution Approach 2:
The patent changes the control parameter from a fixed, conservative charging profile to a dynamic profile based on negative electrode surface potential. By monitoring and responding to surface potential changes, the system optimizes the charging current parameter in real-time, achieving both safety and fast charging performance.
3Reliability
If conventional charging profiles are used with conservative current reduction, then lithium deposition is prevented, but the increases in SOC per unit time slow down notably
Solution Approach 1:
The patent applies dynamics by replacing the static, pre-defined charging profile with a dynamic charging strategy that adjusts current based on real-time surface potential measurements. This enables the system to maintain higher charging rates at the latter stage by dynamically responding to actual lithium deposition conditions rather than following a conservative predetermined profile.
Solution Approach 2:
The patent implements feedback control where the charging current at the latter stage is continuously adjusted based on negative electrode surface potential measurements. This feedback mechanism allows the system to maintain higher productivity by only reducing current when surface potential indicates actual lithium deposition risk, rather than following a conservative predetermined profile.
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 reduces charging time while preventing lithium deposition, enabling faster charging without safety risks by dynamically adjusting the charging current based on the battery's state of charge and temperature conditions.
Implementation Method 1
determining a reference state of charge (SOC) corresponding to a lithium deposition boundary potential in a negative electrode surface potential profile
Data Source
AI summary
A method for determining a charging profile of a battery according to the present disclosure includes determining a reference state of charge (SOC) corresponding to a lithium deposition boundary potential using a test cell, determining a first charging profile by performing a constant current (CC) charging on the test cell until reaching the reference SOC and performing a constant voltage (CV) charging constantly maintaining a voltage between a negative terminal and a positive terminal after reaching the reference SOC, determining a second charging profile by performing the CC charging on the test cell until reaching the reference SOC and performing the CV charging constantly maintaining a voltage between the negative electrode surface and the positive terminal after reaching the reference SOC, and correcting a third charging profile obtained from a battery including a plurality of cells using a difference between the first charging profile and the second charging profile.