Positive Electrode Conductive Aid for Battery Temperature Control
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries with high specific surface area positive electrodes experience a decrease in discharge capacity under high output conditions and an increase in battery temperature during overcharging, which affects their performance and lifespan.
Innovation Solution
A positive electrode for non-aqueous electrolyte secondary batteries is designed with a BET specific surface area of 1 to 3 m2/g, using a combination of conductive aids with different average particle diameters, where the content of the first conductive aid is greater than the second, to control the contact area with the electrolyte and maintain a conductive network, thereby preventing temperature rise and discharge capacity decline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the specific surface area of the positive electrode is increased to improve discharge capacity under high output conditions, then the discharge capacity is improved, but the battery temperature increases during overcharging
Solution Approach 1:
The patent optimizes the specific surface area parameter of the positive electrode to a specific range (0.5 to 3.0 m²/g) to balance discharge capacity and temperature control. This parameter optimization resolves the contradiction by finding the optimal value that provides sufficient surface area for high output performance while limiting excessive surface area that would cause overheating during overcharging.
Solution Approach 2:
The patent uses a composite positive electrode structure combining active material particles with conductive aid particles. This composite structure provides sufficient conductive network and surface area for high discharge capacity while the conductive aid prevents excessive localized heating, thus resolving the temperature-capacity contradiction.
2Reliability
If the specific surface area of the positive electrode is increased to maintain discharge capacity, then the conductive network is improved, but the contact area with electrolyte increases causing temperature rise
Solution Approach 1:
The patent optimizes the specific surface area parameter within a controlled range (0.5 to 3.0 m²/g) to balance conductive network quality and electrolyte contact area. This parameter control ensures sufficient conductivity for reliable performance while limiting excessive contact area that would lead to harmful temperature rise during overcharging.
3Duration of action of stationary object
If the specific surface area is set to 4 m2/g or more to improve lifespan characteristics, then the lifespan is improved, but the discharge capacity decreases under high output conditions
Solution Approach 1:
The patent optimizes the specific surface area parameter to a specific range (0.5 to 3.0 m²/g) that balances lifespan and discharge capacity. This parameter optimization resolves the contradiction by identifying the optimal value range that provides sufficient surface area for good lifespan characteristics while maintaining high discharge capacity under high output conditions, avoiding the capacity loss that occurs at 4 m²/g or higher.
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
The solution effectively suppresses temperature increase during overcharging while securing discharge capacity under high output conditions, ensuring excellent output characteristics and extended battery lifespan.
Implementation Method 1
the conductive aid contains a first conductive aid and a second conductive aid having a larger average particle diameter than the first conductive aid, and the content of the first conductive aid is greater than the content of the second conductive aid in the positive electrode active material layer
Implementation Method 2
The charge and discharge reactions of a battery occur as the ions such as lithium ions are absorbed into and desorbed from an electrode active material
Data Source
AI summary
A positive electrode for non-aqueous electrolyte secondary battery suppresses a decrease in discharge capacity under a high output condition while minimizing an increase in battery temperature in an overcharged state of the battery. The positive electrode includes: a positive electrode current collector; and a positive electrode active material layer that is formed on a surface of the positive electrode current collector, contains a positive electrode active material and a conductive aid, and has a BET specific surface area of from 1 to 3 m2/g, in which the conductive aid contains a first conductive aid and a second conductive aid having a larger average particle diameter than the first conductive aid. The content of the first conductive aid is greater than the content of the second conductive aid in the positive electrode active material layer.