Fluoropolymer Electrodes for High-Temperature Lithium Batteries
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Solution Overview
Problem
Fluorinated carbon electrodes in lithium batteries face discharge rate limitations due to high electronic resistivity, which restricts their performance and capacity, especially at higher currents, and are not suitable for high-temperature applications.
Innovation Solution
Incorporating a fluoropolymer or fluoro-oligomer with carbon-fluorine bonds as the active material in lithium batteries, combined with a substantial quantity of electrically conductive material, enhances the specific capacity and discharge voltage, particularly at elevated temperatures, making them suitable for high-temperature applications like automotive and oil drilling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If fluorinated carbon electrodes are used in lithium batteries, then high specific capacity and energy density are achieved, but discharge rate is limited due to high electronic resistivity
Solution Approach 1:
The patent applies composite materials by combining fluorinated carbon particles with conductive carbon materials (such as acetylene black, graphite, or carbon nanotubes) to create a composite electrode material. This composite structure allows the fluorinated carbon to provide high specific capacity while the conductive carbon network provides pathways for electron transport, thereby resolving the contradiction between high capacity and limited discharge rate caused by electronic resistivity.
2Use of energy by moving object
If fluorinated carbon electrodes are used, then high energy density is achieved, but performance at high temperatures is insufficient
Solution Approach 1:
The patent uses composite materials combining fluorinated carbon with conductive carbon to create electrodes that maintain structural integrity and electrical conductivity at high temperatures. The conductive carbon component provides thermal stability and prevents degradation of the fluorinated carbon structure, enabling the electrode to maintain high energy density performance even at elevated temperatures up to 100°C and above.
3Quantity of substance
If binder materials are minimized to maximize active material content, then capacity is improved, but electrode structural integrity and conductivity may deteriorate
Solution Approach 1:
The conductive carbon material in the composite electrode serves multiple functions: it provides electrical conductivity pathways, acts as a structural framework holding the fluorinated carbon particles, and functions as a conductive additive. This multi-functionality allows the electrode to maintain structural integrity and conductivity without requiring traditional binder materials, thus maximizing active material content while preserving electrode reliability.
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 use of fluoropolymer or fluoro-oligomer electrodes in lithium batteries significantly increases discharge capacity and voltage at high temperatures, enabling their use in demanding applications such as automotive and oil drilling, with discharge voltages up to 3 V and capacities exceeding 300 mAh/g at temperatures above 100°C.
Implementation Method 1
Electrochemical reduction of fluorinated polymers in the presence of lithium has also been reported
Implementation Method 2
Fluorination of graphite allows intercalation of fluorine between the carbon layers
Implementation Method 3
Incorporating a fluoropolymer or fluoro-oligomer with carbon-fluorine bonds as the active material in lithium batteries, combined with a substantial quantity of electrically conductive material, enhances the specific capacity and discharge voltage
Implementation Method 4
the cell overall discharge reaction, first postulated by Wittingham (1975) Electrochem. Soc. 122:526, can be schematized by equation (1)
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
The invention provides lithium and lithium ion batteries in which the active material of one of the electrodes includes a substantial quantity of a fluoropolymer or fluoro-oligomer material having carbon-fluorine bonds. The fluoropolymer or fluoro- oligomer active material may be mixed with a substantial quantity of electrically conductive material, and may also be mixed with subfluorinated carbonaceous materials. The batteries of the invention are useful for elevated temperature applications. The invention also provides methods for electrochemical generation of energy which employ the batteries of the invention at elevated temperatures.