Ceramic-Coated Battery Separator for Electrolyte Wettability
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Solution Overview
Problem
Existing secondary battery separators made of PP or PE materials have poor wettability to electrolyte solutions and poor adhesion to surface coatings due to their non-polar nature and low surface tension, which affects the performance and safety of secondary batteries.
Innovation Solution
A battery separator with a base film and ceramic coating, treated by corona discharge to improve surface energy, and optionally a bonding coating, to enhance adhesion and wettability, ensuring a contact angle difference of less than 15 degrees between layers, thereby improving liquid retention and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PP or PE materials are used as separator, then good pore size distribution and mechanical performance are achieved, but poor wettability to electrolyte solution and poor adhesion to surface coating occur
Solution Approach 1:
The patent applies corona treatment to the PP or PE separator material, which changes the surface parameters (surface tension and polarity) of the base film. This treatment introduces polar groups on the surface, transforming the non-polar characteristics of the original material into a state with improved wettability, while maintaining the bulk mechanical properties of the base film intact.
Solution Approach 2:
The patent creates a composite structure by coating ceramic particles (such as Al2O3, SiO2, TiO2) onto the corona-treated base film. This composite separator combines the mechanical strength and pore structure of the polymer base film with the high surface energy and polarity of the ceramic coating, achieving both good mechanical performance and excellent wettability to electrolyte solution.
2Manufacturing precision
If PP or PE materials are used as separator, then good pore size distribution is achieved, but poor adhesion to surface coating occurs
Solution Approach 1:
The corona treatment modifies the surface energy and chemical composition of the base film without altering its bulk structure or pore distribution. This creates a surface layer with enhanced polarity and bonding capability, allowing the surface coating to adhere strongly while the internal pore structure remains intact for proper electrolyte flow.
Solution Approach 2:
The corona-treated surface acts as an intermediary layer between the non-polar base film and the polar surface coating. The treatment introduces functional groups that serve as bonding sites, mediating the adhesion between the two layers and enabling strong interfacial bonding while preserving the original pore architecture.
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 treated separator enhances adhesion to electrode plates, improves liquid retention, and increases ionic conductivity, leading to better cycle performance and rate characteristics of secondary batteries.
Implementation Method 1
the base film is a base film after corona treatment, power P1 of the corona treatment ranges from 50 W to 200 W, a voltage V1 ranges from 100 V to 230 V, and a time T1 ranges from 0.1 s to 4 s
Data Source
AI summary
The present application provides a battery separator. The battery separator includes a base film and a ceramic coating located on at least one side of the base film, where a difference between a contact angle of the base film and a contact angle of the ceramic coating is less than or equal to 15 degrees. The battery separator in the present application has high adhesion, high liquid retention, and high ionic conductivity, thereby improving the cycle characteristics and the rate characteristics of a battery.