Silane Coupling Agent for Uniform Inorganic Filler Dispersion
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with safety due to shrinkage of micro-porous membranes made from polyolefin resins, leading to potential short circuits and uneven thickness, which affects battery performance and safety, especially when inorganic fillers like oxides agglomerate and deteriorate dispersibility in the paste preparation.
Innovation Solution
A non-aqueous electrolyte secondary battery with an insulating porous membrane composed of uniformly dispersed inorganic fillers and active agents on the surface of electrodes or separator, using a silane coupling agent to prevent agglomeration and ensure uniform thickness, thereby maintaining even electrode distances and preventing direct contact between electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous membrane containing inorganic filler and binder is provided on the electrode surface to prevent short circuits and increase temperature resistance, then safety is improved, but the inorganic filler agglomerates during paste preparation causing non-uniform membrane thickness
Solution Approach 1:
A silane coupling agent is introduced as an intermediary substance between the inorganic filler particles and the binder. This coupling agent prevents agglomeration of the inorganic filler by providing a dispersing effect, while also ensuring good adhesion to the binder. The result is a paste where the inorganic filler remains uniformly dispersed, leading to a porous membrane with uniform thickness that maintains both safety functionality and manufacturing precision.
2Temperature
If inorganic filler such as aluminum oxide, titanium oxide, or magnesium oxide is used to prevent short circuits, then temperature resistance is improved, but the hydrophilic terminal groups on the oxide surface cause moisture adsorption and filler agglomeration
Solution Approach 1:
The silane coupling agent acts as a mediator that modifies the surface of the inorganic filler particles. It bonds to the hydrophilic terminal groups (such as hydroxyl groups) on the oxide surface, replacing them with hydrophobic groups. This prevents moisture adsorption and the subsequent agglomeration that would otherwise occur due to the hydrophilic nature of the oxide surfaces, thereby maintaining stable filler dispersibility while preserving the temperature resistance property.
Solution Approach 2:
The chemical composition of the inorganic filler surface is changed by introducing the silane coupling agent. The hydrophilic terminal groups are replaced with hydrophobic groups, fundamentally altering the surface properties of the filler particles. This parameter change prevents moisture adsorption and agglomeration, ensuring stable dispersibility in the paste while maintaining the high-temperature resistance of the inorganic filler.
3Reliability
If a porous membrane is applied to prevent direct contact between electrodes, then safety is improved, but non-uniform thickness causes variations in electrode distance and battery reaction uniformity
Solution Approach 1:
The silane coupling agent serves as a dispersing intermediary that ensures uniform distribution of inorganic filler particles throughout the paste. By preventing agglomeration at the molecular level, it enables the formation of a porous membrane with consistent thickness when the paste is applied to the electrode surface. This uniform thickness ensures equal electrode spacing across the entire battery, maintaining both safety functionality and uniform battery reaction characteristics.
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 uniformity of the battery reaction, improves charge-discharge cycle characteristics, and maintains safety by preventing temperature increases during abnormal conditions, such as overcharge, by ensuring the insulating porous membrane maintains its integrity and prevents direct contact between electrodes.
Implementation Method 1
an active agent to uniformly disperse the inorganic filler
Implementation Method 2
such oxides have hydrophilic terminal groups, such as hydroxyl groups, on the surface thereof, and thus the oxides are likely to adsorb moisture
Implementation Method 3
This membrane prevents direct contact between the positive and negative electrodes
Implementation Method 4
a thin portion of the membrane is broken by thermal expansion of the positive or negative electrode
Data Source
AI summary
A non-aqueous electrolyte secondary battery has an insulating porous membrane, on at least one of a positive electrode, negative electrode, and separator thereof. The membrane contains an inorganic filler, and an active agent for dispersing the inorganic filler uniformly.