Granular Organic Separator Coating for Heat-Stable Ion Transport
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Solution Overview
Problem
Batteries face challenges with decreasing thermal safety performance and cycling performance when heated, primarily due to the shrinkage of polyolefin-based separators leading to short circuits and reduced ion transport.
Innovation Solution
A separator with a coating of granular organic materials, where M/(H×ρorganic)≥0.4, allows for rational packing and mutual squeezing to reduce shrinkage, forming ion transport channels and enhancing electrolyte infiltration, thereby improving thermal safety and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin-based separator is used, then it provides good chemical stability and electrochemical performance, but it shrinks when heated causing short circuits and reduced thermal safety
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with heat-resistant additives (such as ceramic particles, heat-resistant polymers, or composite coatings) to create a separator that maintains both chemical stability and thermal resistance. The composite structure allows the separator to resist shrinkage at elevated temperatures while preserving the electrochemical benefits of polyolefin.
Solution Approach 2:
The patent changes physical parameters of the separator by modifying its thermal properties through additive incorporation, cross-linking, or structural design. This alters the thermal expansion coefficient and glass transition temperature, enabling the separator to maintain dimensional stability at battery operating temperatures while retaining chemical inertness.
2Reliability
If the separator coating is made thicker to reduce shrinkage, then thermal safety improves, but ion transport channels are reduced and cycling performance decreases
Solution Approach 1:
The patent employs porous materials by incorporating heat-resistant particles (such as ceramic beads or porous structures) that create interconnected void spaces within the coating. These pores serve dual functions: providing thermal stability through particle framework and maintaining ion transport pathways, thus resolving the contradiction between thickness for safety and porosity for conductivity.
Solution Approach 2:
The patent applies local quality by creating a multi-layered or gradient coating structure where different regions have different properties. The outer layer may provide thermal stability while inner regions maintain porosity for ion transport, or the coating density varies through the thickness to optimize both thermal resistance and ionic conductivity in different zones.
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 separator effectively reduces shrinkage-induced short circuits and enhances ion transport, improving thermal safety and cycling performance of batteries.
Implementation Method 1
When the separator is heated, the mutual squeezing between the organic materials can provide a force opposite to a direction of shrinkage of the separator, reducing the shrinkage level of the separator
Implementation Method 2
the overlapping between the organic materials to form more ion transport channels. Through these ion transport channels, the infiltration of the electrolyte into the separator and its storage inside the separator can be enhanced
Data Source
AI summary
This application provides a separator and a preparation method thereof, a secondary battery, and an electric apparatus. The separator includes a substrate and a coating, with the coating being provided on at least one side of the substrate and the coating including organic materials, where a weight per unit area of the coating for a single side is denoted as M, a thickness of the coating for a single side is denoted as H, and a true density of the organic materials is denoted as ρorganic, and the separator satisfies M/(H×ρorganic)≥0.4, where M is in unit of g/m2, H is in unit of μm, and ρorganic is in unit of g/cm3.