Non-Aqueous Battery Electrolyte With FSO3Li Surface-Area Dosing
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in maintaining capacity retention after high-temperature storage due to insufficient distribution of lithium fluorosulfonate (FSO3Li) to the negative electrode, leading to degradation and increased direct current internal resistance.
Innovation Solution
The addition of lithium fluorosulfonate to the electrolyte solution is normalized based on the battery's rated capacity, with specific coefficients for the positive and negative electrodes to ensure sufficient distribution across the negative electrode, improving capacity retention and managing direct current internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium fluorosulfonate (FSO3Li) is added to the electrolyte solution to improve capacity retention after high-temperature storage, then capacity retention is improved, but the amount of FSO3Li distributed to the negative electrode plate may be insufficient because FSO3Li distributes to both positive and negative electrode plates
Solution Approach 1:
The patent applies local quality by establishing different distribution coefficients for FSO3Li at the positive electrode (0.0061 mol/m²) and negative electrode (0.0212 mol/m²). This allows the electrolyte composition to be optimized locally at each electrode surface, ensuring sufficient FSO3Li concentration at the negative electrode while accounting for its distribution to the positive electrode as well.
Solution Approach 2:
The patent changes the parameter of FSO3Li concentration in the electrolyte solution based on the electrode configuration. By calculating the required total amount of FSO3Li using the distribution coefficients and electrode surface areas, the patent determines the optimal concentration parameter to achieve sufficient negative electrode coverage while maintaining overall battery performance.
2Reliability
If excess amount of FSO3Li is added to the electrolyte solution to ensure sufficient distribution to the negative electrode plate, then capacity retention is improved, but direct current internal resistance increases
Solution Approach 1:
The patent applies partial action by calculating the precise amount of FSO3Li needed based on the negative electrode surface area and distribution coefficient (0.0212 mol/m²). Rather than adding excess FSO3Li, the patent determines the minimum required amount using the formula: total FSO3Li = 0.0212 × negative electrode surface area + 0.0061 × positive electrode surface area, achieving sufficient coverage without over-addition.
Solution Approach 2:
The patent uses the distribution coefficients as transfer factors to calculate the required FSO3Li amount. By copying the known distribution behavior (0.0212 mol/m² at negative electrode) into the design formula, the patent can predict and control the FSO3Li distribution without needing to add excessive amounts empirically.
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 enhances post-high-temperature-storage capacity retention and maintains low direct current internal resistance by ensuring adequate FSO3Li distribution across the negative electrode, while maintaining a balance to prevent excessive resistance formation.
Implementation Method 1
FSO3Li forms a film on a surface of a negative electrode active material particle
Implementation Method 2
FSO3Li in the electrolyte solution may be distributed not only to a negative electrode plate but also to a positive electrode plate
Data Source
AI summary
A non-aqueous electrolyte secondary battery satisfies a relationship of an expression (I) “−0.19≤x−(0.0061y+0.0212z)”. x [μmol/Ah] is a value obtained by dividing a total amount of substance of lithium fluorosulfonate included in the electrolyte solution, by the rated capacity. y [m2/Ah] is a value obtained by dividing a product of a BET specific surface area of the positive electrode active material particles and the total mass of the positive electrode active material particles included in the positive electrode plate, by the rated capacity. z [m2/Ah] is a value obtained by dividing a product of a BET specific surface area of the negative electrode active material particles and the total mass of the negative electrode active material particles included in the negative electrode plate, by the rated capacity.