Flat Lithium Primary Battery Cathode Mix for High-Temperature Contact
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Solution Overview
Problem
High-temperature environments cause nonaqueous electrolyte batteries to expand, leading to insufficient electrical connections between battery components, which deteriorates battery characteristics such as increased resistance between the positive electrode and the case.
Innovation Solution
A positive electrode mixture for flat lithium primary batteries is created by mixing particles of a fluorocarbon resin with swellability in an electrolyte and positive electrode active material, where the fluorocarbon resin has an average particle diameter of 10 to 200 μm and a content of 0.2 to 6 parts by mass, allowing it to absorb electrolyte and maintain electrical connections during expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a nonaqueous electrolyte battery is used at high temperature, then the battery can operate in high-temperature environments, but the case expands due to gas generation, causing insufficient electrical connection and deteriorated battery characteristics
Solution Approach 1:
The invention changes the physical state of the fluorocarbon resin from non-swollen to swollen by changing the temperature parameter. At high temperatures, the fluorocarbon resin swells to fill gaps caused by case expansion, maintaining electrical connection. The swelling ratio is controlled to be 1.05 to 1.30 times the original particle diameter, optimizing the balance between filling gaps and maintaining electrode structure.
Solution Approach 2:
The fluorocarbon resin acts as an intermediary material between the case and the positive electrode. It swells at high temperatures to compensate for case expansion, maintaining intimate contact and electrical connection. This intermediary material absorbs the dimensional changes and protects the electrical connection from deterioration.
2Stress or pressure
If the case expands due to gas generation at high temperature, then the battery can withstand internal pressure, but the electrical connection between positive electrode and case becomes insufficient, increasing resistance
Solution Approach 1:
The invention utilizes the temperature-dependent swelling parameter of the fluorocarbon resin. When the battery operates at high temperature and internal pressure increases, the fluorocarbon resin swells to maintain electrical connection. The swelling ratio of 1.05 to 1.30 times the original particle diameter is optimized to compensate for case expansion while maintaining electrode integrity.
Solution Approach 2:
The fluorocarbon resin serves as a mediator that responds to internal pressure changes by swelling. This swelling action maintains intimate contact between the positive electrode and case, ensuring electrical connection is preserved even when the case expands due to internal gas pressure.
3Stability of the object's composition
If a fluorocarbon resin with large particle diameter is used, then the resin can maintain structural stability, but the resin cannot effectively fill gaps and maintain electrical connection during case expansion
Solution Approach 1:
The invention optimizes the particle diameter parameter of the fluorocarbon resin to a specific range of 1 to 10 μm. This size parameter allows the resin particles to effectively fill gaps caused by case expansion while maintaining structural stability. The controlled swelling ratio of 1.05 to 1.30 times the original diameter ensures the swollen particles maintain electrical connection without causing excessive volume increase.
Solution Approach 2:
The fluorocarbon resin provides local quality enhancement at the interface between the case and positive electrode. The resin particles are strategically positioned to fill specific gaps and maintain electrical connection at critical interfaces, while the overall electrode structure maintains its structural stability.
4Reliability
If the fluorocarbon resin content is increased to improve electrical connection, then the electrical connection is maintained, but the electrode structure becomes less stable and may deteriorate
Solution Approach 1:
The invention optimizes the content parameter of fluorocarbon resin to 1 to 10 parts by mass per 100 parts by mass of positive electrode active material. This optimized content parameter ensures sufficient resin is available to maintain electrical connection during case expansion, while preventing excessive resin content that would compromise electrode structural stability and performance.
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 battery maintains high characteristics even at high temperatures, with the fluorocarbon resin swelling to maintain close adhesion between the case and positive electrode, ensuring electrical conduction paths remain intact, thereby preventing a decrease in battery performance.
Implementation Method 1
the fluorocarbon resin with swellability in the nonaqueous electrolyte
Implementation Method 2
the fluorocarbon resin swells to maintain close adhesion between the case and positive electrode
Data Source
AI summary
Disclosed is a flat lithium primary battery including a case, a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, in which the positive electrode, the negative electrode, the separator, and the nonaqueous electrolyte are disposed in the case. The positive electrode includes: a positive electrode active material; and a fluorocarbon resin with swellability in the nonaqueous electrolyte. In the positive electrode, the fluorocarbon resin is present in particulate form. When, on the flat lithium primary battery having been put in an environment with a temperature of 25° C., a high temperature storage test to store the flat lithium primary battery in an environment with a temperature of 125° C. for 100 hours is conducted, the ratio d2/d1 of a particle diameter d2 of the fluorocarbon resin after the high temperature storage test to a particle diameter d1 of the fluorocarbon resin before the high temperature storage test is 1.5 or higher and 3.1 or lower.