Li-Ion Battery Charge Control via Electrode Degradation Segmentation
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Solution Overview
Problem
Lithium ion batteries in vehicles experience non-uniform capacity degradation between the cathode and anode, requiring real-time estimation and use limitation to extend their usable duration.
Innovation Solution
A lithium ion battery charge/discharge control device that uses voltage and current sensors to calculate capacity degradation rates for both the cathode and anode, and adjusts charging and discharging based on comparison with predetermined criterion values to delay capacity degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If charging and discharging are performed intensively to maximize power utilization, then productivity is improved, but capacity degradation accelerates and reliability deteriorates
Solution Approach 1:
The patent segments the battery management into separate control for cathode and anode by calculating their capacity degradation rates independently. This allows differentiated charging/discharging limits to be applied to each electrode based on its specific degradation state, enabling intensive power utilization while preventing either electrode from degrading excessively.
Solution Approach 2:
The patent implements dynamic adjustment of charging and discharging voltage/current limits based on real-time degradation rate calculations. The control section continuously monitors voltage and current, recalculates degradation rates at each measurement point, and adjusts operational parameters dynamically to maximize power output within safe degradation boundaries.
2Device complexity
If uniform degradation control is applied to the entire battery, then device complexity is reduced, but manufacturing precision deteriorates because cathode and anode degradation rates differ
Solution Approach 1:
The patent divides the battery into two independently managed components: cathode and anode. Separate degradation rate calculations are performed for each electrode using their respective voltage and current measurements, enabling precise control that accounts for the different degradation characteristics of each electrode material.
Solution Approach 2:
The patent applies different control strategies to different parts of the battery system. By calculating and comparing degradation rates separately for cathode and anode, the system tailors charging and discharging limits to the specific needs of each electrode, optimizing performance and longevity for each component rather than applying a uniform approach.
3Measurement precision
If degradation estimation is performed only at battery level, then measurement precision is reduced, but device complexity is lowered
Solution Approach 1:
The patent implements separate degradation estimation systems for cathode and anode, each with its own voltage sensor, current sensor, and degradation rate calculation. This segmented measurement approach provides precise tracking of each electrode's health status, enabling accurate identification of which electrode is limiting overall battery performance.
Solution Approach 2:
The patent establishes feedback loops that continuously measure voltage and current at multiple time points, calculate degradation rates, and use this information to adjust charging and discharging operations. The control section receives real-time degradation data from both electrodes and dynamically modifies operational parameters to prevent either electrode from reaching critical degradation thresholds.
Data Source
AI summary
A device that controls charging and discharging of a lithium ion battery (3) that starts an engine starter (1), includes: a voltage sensor (S1) that detects the voltage of the lithium ion battery; a current sensor (S2) that detects the current of the lithium ion battery; and a control section (30) that controls charging and discharging of the lithium ion battery. The control section (30) calculates capacity degradation rates of a cathode and anode of the lithium ion battery based on detected values of the voltage sensor and the current sensor at the time when a first time has elapsed, and at the time when a second time longer than the first time has elapsed, from startup of the engine starter, and limits the charging and discharging of the lithium ion battery based on comparison results between the capacity degradation rates and determination criterion values.