Lithium Battery Separator Surface Modification via Fluorine Gas Treatment
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Solution Overview
Problem
Lithium secondary batteries face issues with dendrite lithium formation at the negative electrode, leading to instability and potential battery breakdown, especially when used in harsh conditions for extended periods.
Innovation Solution
A method of manufacturing a separator for lithium secondary batteries involves creating a porous resin with polar functional groups on its surface by treating it with a gas mixture of N2, O2, or a mixture thereof with F2, forming an insoluble lithium salt layer that inhibits dendrite lithium formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in lithium secondary batteries, then the battery can operate, but dendrite lithium forms on the negative electrode leading to battery breakdown
Solution Approach 1:
The patent introduces a fluorinated porous resin layer as an intermediary between the negative electrode and the electrolyte. This layer mediates the interaction by providing a controlled interface that prevents direct contact between lithium ions and the negative electrode surface, thereby inhibiting dendrite formation while maintaining ionic conductivity.
Solution Approach 2:
The patent employs a porous resin structure with specific pore size and distribution. The porous structure allows lithium ions to pass through while the pore walls provide a physical barrier that prevents dendrite growth. The porosity is optimized to balance ionic conductivity and mechanical barrier function.
2Reliability
If the separator is treated with fluorine gas to form polar functional groups, then dendrite lithium formation is inhibited, but the manufacturing process becomes more complex
Solution Approach 1:
The patent optimizes the fluorine gas treatment parameters including gas concentration, treatment time, and temperature to achieve the desired polar functional group density. By controlling these parameters, the process complexity is managed while ensuring effective dendrite prevention through sufficient surface modification.
Solution Approach 2:
The patent creates a composite structure by combining the porous resin base material with fluorinated surface layers. This composite approach allows the bulk material to maintain its mechanical properties and porosity while the surface layer provides the polar functional groups necessary for dendrite inhibition.
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 method enhances the lifespan and safety of lithium secondary batteries by preventing dendrite lithium growth, ensuring stable performance and preventing battery breakdown over time.
Implementation Method 1
bringing the gas mixture into contact with a porous resin to form a polar functional group on a surface of the porous resin
Implementation Method 2
the polar functional group forms an insoluble lithium salt layer on a surface of a negative electrode
Data Source
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AI summary
The present invention relates to a separator for a lithium secondary battery, including a porous resin comprising one or more polar functional groups selected from the group consisting of -C-F; and -C-OOH and -C=O on a surface thereof, wherein, among the polar functional groups, a molar ratio of -C-OOH and -C=O to -C-F ranges from 0.2:0.8 to 0.8:0.2, and a method of manufacturing the same.