Positive Electrode Surface Area Control for Low-Resistance Li-Ion Cathodes
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Solution Overview
Problem
Existing nonaqueous rechargeable battery manufacturing methods do not effectively optimize the specific surface area of positive electrode active materials, leading to suboptimal discharge and output characteristics due to the formation of newly formed surfaces during the pressing process, which affects internal resistance, overcharge resistance, and storage characteristics.
Innovation Solution
The method involves using positive electrode active materials with a specific surface area of 1.5 to 3.0 m2/g before manufacturing, and adjusting the positive plate's surface area by 0.66 to 1.8 m2/g post-manufacturing, with a density range of 2.2 to 3.0 mg/cm3, incorporating ternary active materials and carbon nanotubes or nanofibers, and applying a nonaqueous solvent to minimize newly formed surfaces and enhance conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the specific surface area of positive electrode active material is increased to improve capacity, then the capacity of the nonaqueous rechargeable battery is improved, but the internal resistance increases and overcharge resistance deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the specific surface area of the positive electrode active material particles within the range of 0.6 to 1.5 m2/g, and by controlling the difference between the specific surface area after and before pressing within 0.66 to 1.8 m2/g. This optimization of physical parameters resolves the contradiction by achieving optimal capacity while maintaining low internal resistance and good overcharge resistance.
2Quantity of substance
If the specific surface area of positive electrode active material is increased to improve capacity, then the capacity of the nonaqueous rechargeable battery is improved, but the storage characteristics deteriorate
Solution Approach 1:
The patent resolves this contradiction by optimizing the specific surface area parameters of the positive electrode active material. By controlling the initial specific surface area to 0.6-1.5 m2/g and the difference after pressing to 0.66-1.8 m2/g, the invention achieves improved capacity while maintaining excellent storage characteristics, preventing the deterioration that would occur with higher surface areas.
3Reliability
If the specific surface area of positive electrode active material is decreased to reduce internal resistance, then the internal resistance is reduced, but the capacity of the nonaqueous rechargeable battery decreases
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal range for the specific surface area (0.6-1.5 m2/g) and controlling the pressing process to maintain the difference within 0.66-1.8 m2/g. This parameter optimization ensures that the capacity is not compromised while achieving low internal resistance, avoiding the capacity loss that would occur with lower surface areas.
4Reliability
If a new indicator for specific surface area is introduced to optimize battery characteristics, then the discharge and output characteristics can be improved, but the manufacturing complexity increases
Solution Approach 1:
The patent introduces a new indicator (the difference between specific surface area after and before pressing, controlled within 0.66-1.8 m2/g) to optimize discharge and output characteristics. While this adds a manufacturing parameter to control, the principle provides clear quantitative guidance that simplifies the optimization process, making the manufacturing process more controllable and less complex than trial-and-error approaches.
Data Source
AI summary
A positive plate for a nonaqueous rechargeable battery includes a positive electrode substrate and a positive electrode mixture layer that contains at least a positive electrode active material. Particles of the positive electrode active material having a specific surface area of a range of 1.5 m2/g to 3.0 m2/g prior to manufacture of the positive plate for the nonaqueous rechargeable battery are used. A difference between a specific surface area of the positive plate for the nonaqueous rechargeable battery after manufacturing the positive plate for the nonaqueous rechargeable battery and the specific surface area of the particles of the positive electrode active material prior to manufacture of the positive plate for the nonaqueous rechargeable battery is in a range of 0.66 m2/g to 1.8 m2/g.