Hybrid Fluorinated Carbon Cathode for High-Rate Lithium Cells
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Solution Overview
Problem
Current lithium electrochemical cells with fluorinated carbon cathodes are limited by low operating voltage and power capabilities due to high electrical resistivity, preventing their use in high-rate applications such as implantable cardiac defibrillators despite their high energy density and stability.
Innovation Solution
A non-aqueous electrochemical cell with a hybrid cathode comprising three distinct fluorinated carbon materials, each with a unique discharge profile and derived from different carbon sources (petroleum coke or pitch), enhancing the operating voltage and energy density to support high-rate applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fluorinated carbon cathode material is used, then energy density is improved, but operating voltage and power capability deteriorate due to high electrical resistivity
Solution Approach 1:
The patent applies composite materials by combining three distinct fluorinated carbon materials (CFx, CFy, CFz) with different fluorination degrees and discharge profiles into a single cathode assembly. This composite approach allows the cathode to achieve both high energy density (from the fluorinated carbon chemistry) and high power capability (from the blended discharge characteristics), resolving the contradiction between energy density and power capability that plagues single-material fluorinated carbon cathodes.
Solution Approach 2:
The patent applies local quality by assigning different functional roles to different components within the cathode mixture. Each fluorinated carbon material (CFx, CFy, CFz) contributes its unique discharge profile and voltage characteristics to specific portions of the overall discharge curve. This allows the cathode to deliver high voltage during early discharge (from higher-fluorination materials) and maintain capacity during later discharge (from lower-fluorination materials), effectively resolving the voltage-resistivity contradiction.
2Ease of manufacture
If single fluorinated carbon material is used, then manufacturing simplicity is improved, but discharge profile versatility deteriorates
Solution Approach 1:
The patent applies merging by combining three separately synthesized fluorinated carbon materials into a single cathode mixture. While each material requires separate synthesis and characterization, the final mixing and assembly process remains relatively simple. This merging approach achieves versatile discharge profiles (covering a wide voltage range from 2.5V to 4.0V) without significantly complicating the overall manufacturing workflow, thus resolving the contradiction between manufacturing simplicity and discharge profile versatility.
Solution Approach 2:
The patent applies universality by designing a cathode system where the blended fluorinated carbon materials serve multiple functions simultaneously: CFx provides high-voltage discharge capability, CFy provides mid-range voltage stability, and CFz provides low-voltage capacity extension. This multi-functional design allows a single cathode assembly to deliver versatile discharge profiles across different rate applications, resolving the contradiction between manufacturing simplicity and discharge profile versatility.
3Use of energy by moving object
If high fluorination degree is used, then energy density is improved, but discharge voltage range deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the cathode material into three distinct fluorinated carbon components (CFx, CFy, CFz) with progressively different fluorination degrees. Each segment handles a specific portion of the discharge voltage range: higher-fluorination materials operate at higher voltages while lower-fluorination materials operate at lower voltages. This segmentation allows the overall cathode to maintain both high energy density (from the fluorinated carbon chemistry) and a wide discharge voltage range (from the distributed fluorination degrees), resolving the contradiction between energy density and voltage range.
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 hybrid cathode achieves a high operating voltage above 2.5 volts and high energy density, enabling the lithium electrochemical cell to handle high-rate pulse discharge applications effectively, such as in implantable cardiac defibrillators, by optimizing the discharge capacity and voltage of each fluorinated carbon material.
Implementation Method 1
Lithium electrochemical cells, which are more commonly referred to as batteries
Implementation Method 2
Li anode/CF cathode cells
Implementation Method 3
a non-aqueous electrolyte which is in fluid communication with the anode, the cathode and the separator
Data Source
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AI summary
The present disclosure relates generally to a cathode material suitable for use in a non-aqueous electrochemical cell that comprises a mixture of fluorinated carbon materials, and more particularly such a cell that comprises a mixture of three fluorinated carbon materials that each have distinct (from each other) discharge profiles (e.g., distinct voltages and capacities). The present disclosure additionally relates to a non-aqueous electrochemical cell comprising such cathode material and, in particular, to such a non-aqueous electrochemical cell that is lithium-based (i.e., a lithium, or lithium ion, non-aqueous electrochemical cell).