Battery Negative Electrode Interface Resistance for Fast Charging
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face challenges in reducing charging time due to limitations in charging load characteristics, primarily attributed to high electrode resistance, which hinders efficient current collection and discharge processes.
Innovation Solution
The development of a negative electrode with a specific interface resistance and volume resistivity ratio (Rs/(ρv×d) within certain ranges, optimized by adjusting the thickness of the negative-electrode mixture layer and interface resistance, to enhance conductivity and charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the electrode resistance is reduced to improve charging load characteristics, then charging time is reduced, but the interface resistance between the negative-electrode mixture layer and current collector becomes a limiting factor
Solution Approach 1:
The invention changes the physical and chemical parameters of the interface between the negative-electrode mixture layer and current collector by controlling the thickness of the mixture layer (35-100 μm) and optimizing the ratio Rs/(ρv×d) to fall within specific ranges (5-20 or 10-38.5). This parameter optimization reduces interfacial resistance and improves charging load characteristics, enabling faster charging without sacrificing reliability.
2Quantity of substance
If a thick negative-electrode mixture layer is used to increase capacity, then the battery capacity increases, but the resistance value increases and charging load characteristics deteriorate
Solution Approach 1:
The invention optimizes the thickness parameter of the negative-electrode mixture layer to fall within the range of 35-100 μm, and further controls the ratio Rs/(ρv×d) to specific ranges. This parameter optimization achieves a balance between capacity and resistance, allowing thick electrodes to maintain low resistance and excellent charging load characteristics.
Solution Approach 2:
The negative-electrode mixture layer comprises a composite structure containing negative-electrode active material, conductive aid, and binder in optimized proportions. This composite material structure ensures adequate capacity while maintaining low resistance through the synergistic effects of the components, particularly the conductive aid that forms a network to reduce overall resistance.
3Reliability
If a thin negative-electrode mixture layer is used to reduce resistance, then charging load characteristics improve, but the battery capacity decreases
Solution Approach 1:
The invention sets the thickness of the negative-electrode mixture layer within the optimized range of 35-100 μm, preventing it from being too thin. This parameter control ensures sufficient capacity while maintaining the Rs/(ρv×d) ratio within specific ranges to achieve excellent charging load characteristics, thus balancing capacity and charging performance.
Data Source
AI summary
A negative electrode for a non-aqueous electrolyte secondary battery including a negative-electrode mixture layer containing a negative-electrode active material on one surface or both surfaces of a current collector, and (1) Rs/(ρv×d) falls within a specific range in accordance with the thickness of the negative-electrode mixture layer, or (2) the negative electrode satisfies a relationship: Rs≤1.67d+b, where Rs is an interface resistance (Ωcm2) between the negative-electrode mixture layer and the current collector, ρv is a volume resistivity (Ωcm) of the negative-electrode mixture layer, and d is the thickness (cm) of the negative-electrode mixture layer. A non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a non-aqueous electrolyte, and wherein the negative electrode is the negative electrode for a non-aqueous electrolyte secondary battery.