Li-Ion Battery Charge Control Based on Ion Diffusion Defects
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Solution Overview
Problem
Existing lithium ion secondary batteries face rapid deterioration due to reversible Li loss, leading to decreased charge-discharge efficiency and energy density, with previous control methods failing to adequately address cycle property without compromising volume energy density.
Innovation Solution
A method for evaluating and controlling the diffusion defect of ions in lithium ion secondary batteries through a determination and control process, including a determination unit, state evaluation unit, and charge-discharge control unit to manage current and voltage applications based on diffusion defect analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If film thickening and increasing of density of electrodes are implemented to increase capacity, then the battery capacity is improved, but rapid deterioration occurs and charge-discharge efficiency decreases
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte by adding specific compounds (cyclic sulfate ester and/or cyclic carboxylate ester) to modify the electrochemical environment. This allows the battery to operate with thicker electrodes and higher capacity while suppressing the rapid deterioration through altered electrolyte composition and properties
2Quantity of substance
If introduction of materials having higher Li-storage ability is implemented to increase capacity, then the battery capacity is improved, but rapid deterioration occurs and charge-discharge efficiency decreases
Solution Approach 1:
The patent introduces cyclic sulfate ester and/or cyclic carboxylate ester as intermediary substances in the electrolyte. These compounds act as mediators that facilitate stable Li-ion transfer between electrodes with high Li-storage ability materials, reducing direct harmful interactions and suppressing rapid deterioration while maintaining high capacity
3Reliability
If reversible Li loss is suppressed by controlling charging and discharging, then cycle property is improved, but volume energy density decreases
Solution Approach 1:
The patent converts the potentially harmful effect of reversible Li loss into a beneficial control mechanism. By adding cyclic sulfate ester and/or cyclic carboxylate ester to the electrolyte, the system enables monitoring and control of Li-ion behavior, transforming the deterioration mechanism into a controllable parameter that can be managed to maintain both cycle property and volume energy density
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
Improves cycle property without lowering volume energy density by suppressing deterioration caused by reversible Li loss.
Implementation Method 1
a determination step of determining a degree of diffusion defect of an ion that performs electric conduction
Implementation Method 2
Li released from a positive electrode during charging is not withdrawn into a negative electrode active substance but precipitates as a Li-containing compound or metallic Li
Data Source
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AI summary
Provided is a technology that can improve a cycle property without lowering a volume energy density. The present technology provides a method for evaluating a secondary battery, including conducting at least: a determination step of determining a degree of diffusion defect of an ion that performs electric conduction; an evaluation step of evaluating a state of the secondary battery on the basis the result of the determination in the determination step; and a control step of controlling states of current application and voltage application on the secondary battery during charging or during discharging of the secondary battery on the basis of the result of the evaluation in the evaluation step.