Composite Separator Coating for High-Temperature Battery Safety
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Solution Overview
Problem
Existing secondary batteries face challenges in balancing high energy density with both electrochemical performance and safety performance, particularly in maintaining cycling performance and safety at high temperatures.
Innovation Solution
A separator comprising a substrate with a coating of inorganic and organic particles, where the organic particles have specific size and structural designs, forming a moderate and non-uniform pore structure that enhances bonding with electrode plates and forms a large-area adhesive film at high temperatures to block ion transmission channels and delay thermal propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If energy density is increased, then battery capacity is improved, but safety performance and cycling performance deteriorate
Solution Approach 1:
The separator uses a composite coating containing both inorganic particles (alumina, silica) and organic particles (polymer beads) with different glass transition temperatures. This composite structure provides thermal stability from inorganic materials while the organic particles form adhesive films at elevated temperatures to block ion transmission, preventing thermal runaway without compromising energy density
Solution Approach 2:
The separator implements local quality differentiation through a dual-particle system where inorganic particles provide structural stability and thermal resistance, while organic particles with specific glass transition temperatures provide temperature-responsive adhesive film formation. This localized functional differentiation allows the separator to maintain performance at high temperatures without requiring overall structural changes that would reduce energy density
2Quantity of substance
If separator thickness is reduced to improve energy density, then ion transmission efficiency deteriorates
Solution Approach 1:
The separator employs a porous substrate structure with controlled pore distribution that maintains high ion transmission efficiency. The porous structure allows adequate ion pathways even in thin separators, while the surface coating of particles provides the necessary thermal safety functions without requiring increased thickness
3Ease of manufacture
If uniform pore structure is used to simplify manufacturing, then bonding performance with electrode plates deteriorates
Solution Approach 1:
The separator uses local quality variation in the form of non-uniform pore structure and dual-particle distribution. The pore size and particle concentration vary across different regions to optimize both bonding performance (where higher particle concentration enhances adhesion) and ion transmission (where pore distribution facilitates ion flow), achieving both goals without complex manufacturing
4Device complexity
If single-material coating is used to reduce complexity, then thermal propagation resistance deteriorates
Solution Approach 1:
The separator uses a composite coating with inorganic particles (alumina, silica) providing thermal stability and structural integrity, combined with organic polymer particles that have different glass transition temperatures. This composite system creates a multi-level thermal response where inorganic materials resist thermal degradation while organic particles form adhesive films at specific temperature ranges, effectively blocking thermal propagation without requiring excessive complexity
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 improves cycling performance and safety performance by maintaining ion transmission and reducing thermal propagation, while optimizing energy density and safety through a synergistic effect of inorganic and organic particles with tailored sizes and structures.
Implementation Method 1
the first and second organic particles will form a large-area adhesive film structure, so as to reduce or block the ion transmission channels and delay the thermal propagation of the battery
Data Source
AI summary
The present application relates to a separator, comprising a substrate and a coating formed on at least one surface of the substrate; wherein the coating comprises inorganic particles and organic particles, the organic particles comprise first organic particles and second organic particles both embedded in the inorganic particles and forming protrusions on the surface of the coating, the first organic particles have a number-average particle size of ≥8 μm; the second organic particles have a number-average particle size of ≥2 μm, and at least part of the second organic particles comprise a core structure and a shell structure. The present application also relates to a secondary battery comprising the separator, a device comprising the secondary battery and a method for preparing the separator.