Secondary Battery Controller Adjusting SOC Limits for Capacity Maintenance
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Solution Overview
Problem
Lithium-ion secondary batteries experience significant capacity reduction due to deterioration, leading to a reduced usable energy amount, as the positive electrode potential shifts after deterioration, affecting the SOC use region and battery performance.
Innovation Solution
A controller for secondary batteries that adjusts the lower limit SOC setting value based on the shift in positive electrode potential due to deterioration, using a memory section to store initial and post-deterioration potentials, and computing the post-deterioration capacity maintenance value to maintain the SOC use region and prevent capacity reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed lower limit SOC setting value is used to define the battery use range, then the battery can be operated within a safe potential window, but the usable battery capacity significantly reduces after deterioration due to positive electrode potential shift
Solution Approach 1:
The lower limit SOC setting value is made dynamic rather than fixed. The controller dynamically adjusts the lower limit SOC setting value based on the detected positive electrode potential shift, allowing the battery use range to adapt to deterioration while maintaining safety margins and preserving usable capacity
Solution Approach 2:
The controller changes the parameter (lower limit SOC setting value) based on the detected positive electrode potential shift. By detecting the shift in positive electrode potential and accordingly adjusting the lower limit SOC setting value, the system compensates for deterioration effects and maintains optimal battery utilization
2Quantity of substance
If the lower limit SOC setting value is reduced to compensate for potential shift, then the SOC use region is secured, but the battery may operate at lower potentials that could affect performance
Solution Approach 1:
The controller implements a feedback mechanism where it detects the positive electrode potential, calculates the shift from the initial value, and uses this information to adjust the lower limit SOC setting value. This closed-loop feedback ensures that the battery operates within optimal parameters while compensating for deterioration
Solution Approach 2:
The controller preliminarily determines the appropriate lower limit SOC setting value by detecting the positive electrode potential shift before significant capacity loss occurs. This preliminary adjustment prevents the battery from operating in detrimental potential regions while maximizing usable capacity
Data Source
AI summary
A controller is a controller for a secondary battery for which a lower limit SOC setting value and an upper limit SOC setting value are set in advance and that is used in a use potential width determined by the lower limit SOC setting value and the upper limit SOC setting value. This controller is configured to: compute a post-deterioration positive electrode use minimum potential that is shifted from an initial positive electrode use minimum potential to a high potential side due to the deterioration of the secondary battery; and reset the lower limit SOC setting value to a value that is lower than the lower limit SOC setting value set in advance and that is higher than the SOC 0% in accordance with a shift amount as a difference between the post-deterioration positive electrode use minimum potential and the initial positive electrode use minimum potential.