Lithium Battery Separator Coating Slurry with High Adhesion and Ionic Conductivity
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Solution Overview
Problem
Lithium-ion battery separators face issues with low ionic conductivity and unsatisfactory bonding ability due to coatings made from polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), or acrylic binders, leading to increased internal resistance and impaired performance.
Innovation Solution
A coating slurry with high adhesion and ionic conductivity is developed using a ternary composite conductive adhesive (PEAE) prepared through in-situ polymerization of PEDOT, PEO, and PAA, combined with a dispersing agent and wetting agent, ensuring even distribution and improved bonding on a basal membrane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating is applied to the lithium battery separator using PVDF, PVA, or acrylic binder, then the separator structure is protected, but the ionic conductivity decreases and adhesion is insufficient
Solution Approach 1:
The patent uses a composite coating material consisting of polyacrylic acid (PAA) as binder, polyethylene oxide (PEO) as filler, and poly(3,4-ethylenedioxythiophene) (PEDOT) as conductive additive. This composite structure combines the protective function of the binder with the ionic conductivity of PEO and the electrical conductivity of PEDOT, resolving the contradiction between protection and ionic conductivity/adhesion performance.
Solution Approach 2:
The patent optimizes the mass ratios of PAA, PEO, and PEDOT in the coating layer to achieve the best balance between adhesion, ionic conductivity, and protection. By adjusting the composition parameters of the composite material, the coating provides sufficient protection while maintaining high ionic conductivity and strong adhesion to the separator.
2Reliability
If a coating is applied to the lithium battery separator, then the separator structure is protected, but the internal resistance increases greatly
Solution Approach 1:
The composite coating material combines PEO with high ionic conductivity and PEDOT with electrical conductivity, creating a coating that protects the separator while maintaining low internal resistance. The synergistic effect of the composite materials ensures that the coating does not significantly increase the battery's internal resistance despite providing structural protection.
3Object-generated harmful factors
If PEAE is used as coating material, then adhesion and ionic conductivity are improved, but the material cannot be directly and evenly coated on separator
Solution Approach 1:
The patent uses polyacrylic acid (PAA) as a binder that acts as an intermediary between the separator and the conductive adhesive PEAE. The PAA binder provides good adhesion to the separator surface and enables uniform coating, while PEAE contributes adhesion enhancement and ionic conductivity. This intermediary approach resolves the contradiction between improved performance and coating processability.
Solution Approach 2:
The patent optimizes the mass ratio of PAA to PEAE in the coating composition to achieve both good coating processability and high performance. By adjusting the composition parameters, the coating slurry achieves proper viscosity and flow characteristics for uniform application, while maintaining the high adhesion and ionic conductivity properties of PEAE.
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 enhances the ionic conductivity and adhesion of lithium battery separators, reducing internal resistance and improving capacity retention, as demonstrated by lower internal resistance and higher capacity retention compared to existing PVDF coatings.
Implementation Method 1
PEAE (as a main component), where the PEAE is prepared from PEDOT, PEO, and PAA through in-situ polymerization
Implementation Method 2
mixing PEAE, a dispersing agent, a wetting agent, and a solvent, and subjecting a resulting mixture to dispersion to obtain the coating slurry
Data Source
AI summary
A coating slurry with high adhesion and high ionic conductivity, a preparation method thereof, and a lithium battery separator are provided. The coating slurry with the high adhesion and the high ionic conductivity includes: PEAE: 1 to 60 parts; a dispersing agent: 0.01 to 10 parts; a wetting agent: 0.01 to 15 parts; and a solvent: 100 parts. The PEAE can be evenly coated on a basal membrane to form a lithium battery separator, which solves the problem that pure PEAE cannot be directly and evenly coated on a separator. The PEAE is coated on the basal membrane for the first time to prepare the lithium battery separator, which ensures that the lithium battery separator has characteristics of the high adhesion and the high ionic conductivity.