Battery Separator Inorganic Coating High Temperature Stability
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Solution Overview
Problem
Conventional lithium ion battery separators face challenges with high temperature resistance, strength retention, and heat shrinkage, as they often lose strength and stability when exposed to elevated temperatures, leading to potential short circuits and safety issues.
Innovation Solution
A lithium ion battery separator with a substrate comprising a support layer and a dense layer, coated with an inorganic coating composed of alumina, silica, or magnesium hydroxide particles, dispersants, water-retaining agents, and adhesive resins, which maintains strength and heat stability even after treatment at 300°C for 1 hour, ensuring a heat shrinkage rate of no more than 2%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyolefin separator is used, then mechanical properties and chemical stability are excellent, but temperature resistance is limited and strength is lost above 150°C
Solution Approach 1:
The patent uses a composite structure combining polyolefin base material with ceramic coating layer (alumina, silica, or boehmite particles). The ceramic coating provides high temperature resistance while the polyolefin substrate maintains mechanical integrity, creating a composite separator that retains strength at temperatures where conventional polyolefin separators would fail.
Solution Approach 2:
The patent modifies the surface properties of the polyolefin separator by coating it with ceramic particles, changing the thermal parameters of the separator. The ceramic coating raises the effective operating temperature from below 150°C to above 200°C while maintaining the mechanical properties of the underlying polyolefin structure.
2Temperature
If non-woven fabric separator is used, then high temperature resistance is improved, but strength is low and pores are large causing micro-short circuits
Solution Approach 1:
The patent combines the advantages of non-woven fabric (high temperature resistance) with ceramic coating to create a composite separator. The ceramic particles fill and reinforce the pore structure, reducing pore size to prevent micro-short circuits while maintaining the high temperature stability of the non-woven fabric substrate.
Solution Approach 2:
The patent applies ceramic coating specifically to the non-woven fabric separator surface, creating a localized enhancement of pore structure and strength where needed. The ceramic particles are distributed within the pore structure to provide local reinforcement and pore size control without compromising the overall high temperature resistance of the non-woven fabric.
3Temperature
If ceramic coating is applied to polyolefin separator, then thermal stability is improved, but strength is completely lost when polyolefin melts at high temperature
Solution Approach 1:
The patent creates a composite separator where the ceramic coating provides thermal stability up to 200°C and above, while the polyolefin substrate maintains mechanical strength. The synergistic combination allows the separator to retain both thermal stability and strength at high temperatures where conventional ceramic-coated separators would fail.
Solution Approach 2:
The patent optimizes the ceramic coating composition and thickness to achieve the right balance between thermal stability and mechanical strength. By controlling the ceramic particle size, distribution, and coating weight, the patent ensures that the separator maintains adequate strength while achieving high temperature resistance.
4Ease of manufacture
If support layer uses synthetic fibers, then manufacturing is easier, but lyophilic performance is poor and air bubbles are introduced forming large holes
Solution Approach 1:
The patent modifies the surface properties of synthetic fibers in the support layer by treating them to improve lyophilic performance. This allows the support layer to effectively bind electrolyte solution while maintaining manufacturing ease and avoiding the formation of large holes or air bubbles that would compromise separator integrity.
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 provides a separator with enhanced high-temperature resistance, strength retention, and improved porosity, effectively addressing the limitations of existing separators by maintaining structural integrity and isolation at high temperatures, thus ensuring safer and more reliable battery performance.
Implementation Method 1
an inorganic coating composed of alumina, silica, or magnesium hydroxide particles... which maintains strength and heat stability even after treatment at 300°C for 1 hour, ensuring a heat shrinkage rate of no more than 2%
Implementation Method 2
an inorganic coating composed of alumina, silica, or magnesium hydroxide particles, dispersants, water-retaining agents, and adhesive resins
Data Source
AI summary
A battery separator and a preparation method therefor are provided. The separator includes a lithium ion battery separator substrate and an inorganic coating, the lithium ion battery separator substrate consists of a support layer and a dense layer, and the inorganic coating is coated on the dense layer; the separator has excellent high-temperature resistance, and still has good strength retention and the heat shrinkage rate thereof is no more than 2% after treatment at 300° C. for 1 h, and thus ensures the stability and isolation of the rigid structure of the separator coating at high temperatures; the substrate has a uniform and compact double-layer structure, effectively controls phenomena such as pinholes and filler particles fall-off in a subsequent coating process, and meets the requirements of lithium ion battery separators with respect to heat resistance, porosity and strength, thus having excellent comprehensive performance.