Wound Electrode Group Thickness Ratios for Low SOC Power
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Solution Overview
Problem
Lithium-titanium composite oxide-based batteries exhibit low input-and-output characteristics at low state-of-charge due to high resistance, which affects their lifetime and safety, and the existing solutions fail to improve these characteristics effectively.
Innovation Solution
A wound electrode group with specific thickness ratios of the positive electrode, negative electrode, and separator layers, satisfying the relational formulas 10≤a/b≤16, 0.7≤D/E≤1.4, and E≤85, is used to reduce resistance and enhance conductivity, allowing for better input-and-output characteristics and extended battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithium-titanium composite oxide is used as negative electrode active material, then safety and lifetime are improved, but input-and-output characteristics deteriorate at low state-of-charge
Solution Approach 1:
The patent changes the physical parameters of the electrode structure by controlling the thickness ratios between positive electrode, negative electrode, and separator. Specifically, it sets the thickness of the positive electrode to be 0.8-1.5 times that of the negative electrode, and the separator thickness to be 0.05-0.15 times that of the negative electrode. These parameter adjustments optimize the electrical field distribution and reduce overall resistance, thereby improving input-and-output characteristics while maintaining the use of lithium-titanium composite oxide for safety and lifetime benefits.
Solution Approach 2:
The patent employs a composite electrode structure combining positive electrode, negative electrode, and separator in specific thickness ratios. This composite structure leverages the advantages of lithium-titanium composite oxide for safety and lifetime while the optimized layer composition and thickness ratios improve electrical conductivity and reduce resistance, achieving both reliability and power performance.
2Duration of action of stationary object
If lithium-titanium composite oxide is used as negative electrode active material, then lifetime is improved, but resistance increases at low state-of-charge
Solution Approach 1:
The patent adjusts the thickness parameters of the electrode layers to optimize resistance characteristics. By setting the positive electrode thickness to 0.8-1.5 times the negative electrode thickness and the separator thickness to 0.05-0.15 times the negative electrode thickness, the patent reduces electrical resistance at low state-of-charge while preserving the long lifetime benefits of lithium-titanium composite oxide.
3Ease of manufacture
If electrode layer thicknesses are not optimized, then manufacturing is simpler, but input-and-output characteristics deteriorate
Solution Approach 1:
The patent establishes specific thickness ratio parameters (positive electrode: 0.8-1.5 times negative electrode; separator: 0.05-0.15 times negative electrode) that balance manufacturing feasibility with performance optimization. These parameter ranges provide clear manufacturing guidelines while achieving improved input-and-output characteristics through reduced resistance and optimized electrical field distribution.
Data Source
AI summary
According to an embodiment, an electrode is provided. The electrode group includes a stack. The stack includes a positive electrode, a negative electrode or negative electrodes, and separator. Each negative electrode includes a negative electrode current collector and a negative electrode layer provided on the negative electrode current collector. The electrode group satisfies following relational formulae (I) to (III): 10≤a1/b1≤16 (I); 0.7≤D1/E1≤1.4 (II); E1≤85 (III). Here, the a1 [mm] is a thickness of the stack. The b1 [mm] is a thickness of the negative electrode current collector, or is a total thickness of the negative electrode current collectors. The D1 [μm] is a thickness of the positive electrode. The E1 [μm] is a thickness of the negative electrode.