Lithium Ion Battery Charging Method with Dynamic Current Control
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Solution Overview
Problem
Current lithium ion secondary battery charging methods do not account for the diffusion coefficient of lithium ions in the negative electrode, leading to reduced charging efficiency and battery degradation due to excessive heat generation.
Innovation Solution
A charging method that adjusts the charging current based on the charge rate, with specific average and maximum current values (A, B, and C) in different charge rate ranges, ensuring a ratio of CMAX to CMIN between 1.01 to 3.00, to minimize heat generation and maintain battery efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current is increased to reduce charging time, then the charging speed is improved, but the heat generation increases and battery characteristics deteriorate
Solution Approach 1:
The charging current is dynamically adjusted based on the charge rate range. The method divides charging into multiple stages with different current values (A, B, C) corresponding to different charge rate ranges. As the battery charges and the charge rate changes, the current is automatically adjusted to optimize both charging speed and heat control, rather than using a fixed high current throughout.
Solution Approach 2:
The method changes the charging current parameter according to the charge rate. By establishing specific relationships between charge rate ranges and current values (A>B>C), the system adapts the charging parameters to the battery's state, allowing high current when the battery can accept it (low charge rate) and reducing current when heat generation becomes problematic (high charge rate).
2Productivity
If the charging current is increased to reduce charging time, then the charging speed is improved, but the battery cycle characteristics are reduced
Solution Approach 1:
The charging current is dynamically adjusted based on the charge rate range. The method divides charging into multiple stages with different current values (A, B, C) corresponding to different charge rate ranges. As the battery charges and the charge rate changes, the current is automatically adjusted to optimize both charging speed and heat control, rather than using a fixed high current throughout.
Solution Approach 2:
The method changes the charging current parameter according to the charge rate. By establishing specific relationships between charge rate ranges and current values (A>B>C), the system adapts the charging parameters to the battery's state, allowing high current when the battery can accept it (low charge rate) and reducing current when heat generation becomes problematic (high charge rate).
3Productivity
If constant-current charging is performed at high current until set voltage, then the charging efficiency is improved, but the diffusion coefficient limitation causes heat generation and performance degradation
Solution Approach 1:
The charging process is segmented into multiple charge rate ranges with different current values. Instead of using a single constant current, the method divides the charging process into stages (with current values A, B, C) corresponding to different charge rate ranges. This segmentation allows the system to operate at high efficiency when the battery can accept high current while switching to lower currents when the diffusion coefficient becomes limiting.
Solution Approach 2:
The charging current is dynamically adjusted based on the charge rate range. The method divides charging into multiple stages with different current values (A, B, C) corresponding to different charge rate ranges. As the battery charges and the charge rate changes, the current is automatically adjusted to optimize both charging speed and heat control, rather than using a fixed high current throughout.
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 suppressing heat generation and preserving battery characteristics, such as charge-discharge cycle performance, by optimizing current values according to the diffusion coefficient of lithium ions.
Implementation Method 1
the diffusion coefficient of lithium ions in a negative electrode has become clear recently... the diffusion coefficient of lithium ions in a negative electrode means a physical constant representing the ease of movement of lithium ions in a negative electrode
Data Source
AI summary
A method for charging a lithium ion secondary battery of the present invention includes a first step and a second step. In the first step, A, B, and C satisfy the relationship A>B and B<C, where A represents an average charging current value in the range where a charge rate of the lithium ion secondary battery is 0% or more and less than 40%, B represents an average charging current value in the range where the charge rate is 40% or more and 60% or less, and C represents an average charging current value in the range where the charge rate is more than 60%. In the first step, the ratio of CMAX to CMIN (CMAX/CMIN) is 1.01 to 3.00, where CMAX represents the maximum value of the charging current value and CMIN represents the minimum value of the charging current value.