Li/CFx Cell Rod Current Collector Offset Flats
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Solution Overview
Problem
Existing electrochemical cells face challenges in maintaining intimate contact between fluorinated carbon (CFx) cathode active material and the rod-shaped cathode current collector, leading to potential axial movement and delamination, which is critical for reliable power supply in implantable medical devices.
Innovation Solution
The CFx material is formed into a cylindrically shaped body and pressed into intimate contact with a rod-shaped cathode current collector that has angularly offset flat areas to prevent axial movement, and the assembly is housed in a cylindrical casing with a terminal pin and nonaqueous electrolyte for hermetic sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the CFx cathode active material is pressed into contact with the rod-shaped cathode current collector, then electrical contact is improved, but axial movement and delamination occur
Solution Approach 1:
The patent applies asymmetry by providing the cathode current collector rod with flat areas at angularly offset positions around its circumference. This asymmetric geometry prevents axial movement of the CFx material by creating mechanical interlocking features, while maintaining intimate electrical contact between the cathode active material and current collector.
2Strength
If the rod-shaped cathode current collector is made solid for structural integrity, then mechanical strength is improved, but contact area with CFx material is reduced
Solution Approach 1:
The patent applies local quality by creating flat areas at specific locations on the rod-shaped current collector. These localized flat regions provide enhanced contact surfaces for the CFx material while maintaining the overall solid cylindrical structure for mechanical strength. The flat areas are positioned at angularly offset locations to optimize both contact area and prevent axial movement.
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
This configuration ensures stable and reliable electrical energy conversion, preventing delamination and axial movement, making the cell suitable for powering implantable medical devices like cardiac pacemakers and neurostimulators.
Implementation Method 1
The present invention generally relates to the conversion of chemical energy to electrical energy. Preferred cell chemistry is of a lithium anode and a fluorinated carbon (CFx) cathode. The electrode assembly is activated with a nonaqueous electrolyte hermetically sealed inside the casing.
Implementation Method 2
The electrode assembly is activated with a nonaqueous electrolyte hermetically sealed inside the casing.
Implementation Method 3
The preferred CFx material is formed into a cylindrically shaped body pressed into intimate contact with the rod-shaped cathode current collector.
Data Source
AI summary
An electrochemical cell comprising a cathode of a powder material pressed into intimate contact with a rod-shaped current collector and an anode at least partially wrapped around the cathode is described. The cathode current collector is preferably provided with a plurality of offset flats offset with respect to each other. This helps prevent the cathode active material from sliding off of the rod-shaped current collector. The anode has spaced apart edges at opposite ends of its width that form a gap with the anode wrapped around the cathode. This helps in sliding the anode/cathode electrode assembly into a cylindrical tube comprising the cell casing. A preferred chemistry is a lithium/CFx activated with a nonaqueous electrolyte.