Silane-Treated Alumina Separator Coating for HF-Stable Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional polyolefin separators in lithium-ion batteries suffer from low wettability by polar electrolytes, mechanical instability at high temperatures, and potential gas formation due to hydrofluoric acid (HF) production, posing safety risks and reducing battery performance.
Innovation Solution
A separator coated with a hydrophobic surface-treated alumina layer, combined with a binder, enhances compatibility and stability, preventing HF formation and maintaining battery performance at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyolefin separators are used, then mechanical strength and chemical stability are improved, but wettability by polar electrolytes deteriorates
Solution Approach 1:
The patent applies composite materials by coating polyolefin separator with a layer containing inorganic particles (alumina, silica, titania, zirconia, magnesia) and binder. This composite structure combines the mechanical strength of polyolefin with the hydrophilic properties of inorganic particles, achieving both good mechanical strength and improved wettability by polar electrolytes.
2Ease of manufacture
If polyolefin separators are used, then cost is reduced, but thermal stability deteriorates
Solution Approach 1:
The patent uses composite materials by combining polyolefin separator with inorganic particles having high thermal stability (alumina, silica, titania, zirconia, magnesia). The inorganic coating layer maintains structural integrity at high temperatures, preventing separator shrinkage and electrode short circuit while keeping the base polyolefin structure for cost-effectiveness.
Solution Approach 2:
The patent changes the thermal parameters of the separator by introducing inorganic particles with high melting points and thermal stability. This modifies the thermal behavior of the separator, enabling it to maintain mechanical properties at elevated temperatures up to 150°C or higher, while the polyolefin base maintains low cost.
3Reliability
If silica particles are used in coating layer, then wettability is improved, but gas formation increases due to HF reaction
Solution Approach 1:
The patent extracts silica from the inorganic particle composition and replaces it with alumina and other inorganic particles that do not react with HF to form gases. This eliminates the harmful gas formation issue while maintaining the wettability improvement provided by inorganic particle coating.
Solution Approach 2:
The patent converts the potential harm of inorganic particle selection by deliberately choosing alumina and other HF-stable particles that prevent harmful gas formation. The inorganic coating still provides wettability improvement and thermal stability, but without the silica-HF reaction hazard.
4Temperature
If inorganic particles are coated on separator, then thermal stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-surface treating inorganic particles with silane coupling agents before coating. This pre-treatment creates reactive groups on particle surfaces that facilitate bonding to the binder and separator, simplifying the coating process and improving adhesion without requiring complex post-treatment steps.
Solution Approach 2:
The patent uses silane coupling agents as intermediaries between inorganic particles and the binder/separator matrix. The silane forms chemical bonds with both the inorganic particle surface and the organic binder, creating strong interfacial adhesion and simplifying the overall coating process by enabling direct one-step coating without complex surface preparation.
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 alumina-coated separator improves battery capacity retention and safety by reducing AC impedance and HF content, maintaining high efficiency even after multiple charge-discharge cycles.
Implementation Method 1
surface treated with a silane of general formula (I) or (la)
Implementation Method 2
preventing HF formation and maintaining battery performance
Implementation Method 3
The separator prevents the direct contact between the two electrodes
Data Source
AI summary
The invention relates to a separator for a lithium-ion battery, comprising an organic substrate coated with a coating layer comprising a binder and alumina particles, surface treated with a silane of general formula (I) or (Ia), a method for synthesis of the separator and the use thereof in lithium-ion batteries.