Nonaqueous Battery Anode Density and Electrolyte for Fast Charge Retention
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries, particularly those used in hybrid electric vehicles, face limitations in charging opportunities and capacity deterioration at high temperatures, with insufficient input characteristics and storage characteristics.
Innovation Solution
A nonaqueous electrolyte secondary battery configuration featuring a negative electrode active material layer with carbon material particles having an average circularity of 0.86 or more and an apparent density of 1.30 g/cm3 to 1.69 g/cm3, combined with a nonaqueous electrolyte containing 1% to 30% by volume of a carboxylate ester with 4 or less carbon atoms, enhancing both input and high-temperature storage characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the negative electrode density is increased to enhance battery capacity, then the battery capacity per volume increases, but the input characteristics become insufficient
Solution Approach 1:
The invention changes the particle shape parameter of the negative electrode active material from conventional irregular shapes to spherical shapes with high circularity (0.94 or more). This parameter change enables the negative electrode to achieve both high density (enhancing capacity per volume) and excellent input characteristics, as the spherical particles provide efficient electrolyte penetration and lithium ion insertion/extraction pathways while maintaining high packing density.
2Speed
If the battery is operated at high temperatures, then the charging speed may be improved, but the capacity deteriorates significantly
Solution Approach 1:
The invention changes the particle morphology parameter to spherical shapes with high circularity (0.94 or more), which fundamentally alters the thermal behavior of the negative electrode. The spherical particles provide uniform stress distribution during thermal expansion and contraction, reduce localized hot spots, and enable stable solid electrolyte interface (SEI) formation that prevents capacity deterioration even at high temperatures while maintaining fast charging capability.
3Quantity of substance
If the negative electrode density is increased to 1.7 g/cm3 or higher, then the capacity per volume is maximized, but the electrolyte impregnation becomes insufficient
Solution Approach 1:
The invention changes the particle shape parameter to spherical forms with high circularity (0.94 or more), which fundamentally improves electrolyte impregnation efficiency. The spherical particles create uniform interparticle voids that facilitate complete electrolyte penetration even at high densities of 1.7 g/cm3 or higher, ensuring sufficient lithium ion transport pathways throughout the entire negative electrode structure while maintaining maximum capacity per volume.
Data Source
AI summary
Provided is a nonaqueous electrolyte secondary battery having excellent input characteristics and excellent high-temperature storage characteristics. A nonaqueous electrolyte secondary battery disclosed here includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The negative electrode includes a negative electrode active material layer containing a negative electrode active material. The negative electrode active material includes carbon material particles having an average circularity of 0.86 or more. The negative electrode active material layer has an apparent density of 1.30 g/cm3 to 1.69 g/cm3. The nonaqueous electrolyte contains a nonaqueous solvent and an electrolyte salt. The nonaqueous solvent contains 1% by volume to 30% by volume of a carboxylate ester having 4 or less carbon atoms.