Lithium-Ion Battery Separator Composition for Internal Metal Trapping
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Solution Overview
Problem
Conventional lithium ion secondary battery separators can only display desired functions like metal trapping ability at the surface layer, limiting their efficiency in effectively preventing transition metal ion elution and maintaining battery safety and performance.
Innovation Solution
A composition for lithium ion secondary battery separators is developed, incorporating a liquid medium and a specific compound with a function-displaying functional group, such as an acidic group, within a microporous resin substrate, allowing for deep penetration and efficient support of the functional group inside the separator substrate, enhancing metal trapping ability and cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compound with metal trapping ability is included only in a porous membrane layer on the separator surface, then the separator can provide metal trapping function at the surface, but the function cannot be efficiently displayed throughout the entire separator
Solution Approach 1:
The patent transitions from surface-only functionalization (2D) to volumetric functionalization (3D) by introducing compounds into the porous substrate interior. This dimensional expansion allows the metal trapping function to be displayed throughout the entire separator volume, not just at the surface, thereby resolving the contradiction between providing surface function and achieving efficient overall function display.
Solution Approach 2:
The patent utilizes the porous structure of the separator substrate to accommodate and support the metal trapping compounds within the pore spaces. By filling the pores with the functional compound, the separator achieves both surface and internal metal trapping capability, efficiently displaying the desired function throughout the entire separator structure.
2Reliability
If a compound is introduced into the separator substrate to enhance metal trapping ability, then the functional group support is improved, but the compound may block pores and reduce ion permeability
Solution Approach 1:
The patent applies local quality by concentrating the metal trapping compounds specifically within the pore regions of the separator substrate rather than uniformly distributing them throughout. This localized placement ensures that the functional groups are positioned to effectively trap metal ions while minimizing pore blockage, as the compounds occupy only the pore spaces and leave channels open for ion transport.
Solution Approach 2:
The patent leverages the porous structure to house the functional compounds within the pore volume without completely filling or blocking the pores. The porous architecture allows the compounds to be supported inside the pores while maintaining open pathways for ion permeability, thus resolving the contradiction between enhancing metal trapping ability and maintaining ion transport.
3Reliability
If a high concentration of functional compound is used to maximize metal trapping ability, then the desired function is enhanced, but the manufacturing precision and uniformity of the separator may be compromised
Solution Approach 1:
The patent applies partial action by introducing the functional compound at an optimized concentration that is sufficient to provide the desired metal trapping ability without excessive amounts that would cause poor uniformity. The compound content is controlled within a specific range (0.1-10 wt% relative to separator weight), which is enough to achieve effective metal trapping while maintaining good manufacturing precision and separator uniformity.
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 solution enables lithium ion secondary batteries to exhibit improved metal trapping ability and cycle characteristics by ensuring the functional group is well-supported within the separator substrate, thereby enhancing battery performance and safety.
Implementation Method 1
a separator substrate comprising a microporous membrane made from a resin, allowing for deep penetration and efficient support of the functional group inside the separator substrate
Implementation Method 2
a first compound including a function-displaying functional group... including a specific compound with a function-displaying functional group, such as an acidic group... enhancing metal trapping ability
Data Source
AI summary
Provided are a composition for a lithium ion secondary battery separator containing: a liquid medium; and 40 mass % or less of a first compound including a function-displaying functional group and having a molecular weight of 50,000 or less, and having a surface tension of 15 mN/m to 30 mN/m, and a two-part composition for a lithium ion secondary battery separator including: a first liquid containing a first compound and first liquid medium; and a second liquid containing a second compound and second liquid medium, wherein the first compound includes a function-displaying functional group and has a molecular weight of 50,000 or less, the second compound is reactive with the first compound and has a molecular weight of 50,000 or less, and the first and second liquids each contain the corresponding compound in a proportion of 40 mass % or less and have a surface tension of 15 mN/m to 30 mN/m.