Lithium Battery Separator Coating for Dendrite and Short-Circuit Control
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Solution Overview
Problem
Current polymer separators for lithium secondary batteries have weak heat resistance and mechanical strength, posing safety risks and limiting the life and performance of the batteries.
Innovation Solution
A separator with a substrate coated with a solid electrolyte first layer and a lithium compound second layer, providing improved ion and electron conductivity, and uniform pore distribution to enhance lithium ion transport and prevent internal short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer separator is used in lithium secondary batteries, then the battery can operate with lithium ion transport, but the heat resistance and mechanical strength are weak, posing safety risks
Solution Approach 1:
The patent applies composite materials by combining a polyolefin base layer with ceramic coating layers (alumina, silica, boehmite). This composite structure integrates the advantages of both materials: the polymer provides flexibility and ion transport, while the ceramic coating enhances mechanical strength, heat resistance, and dimensional stability, thereby resolving the contradiction between safety and mechanical strength.
Solution Approach 2:
The patent changes the physical and chemical parameters of the separator by controlling the thickness of ceramic coating layers (1-10 μm), adjusting porosity (30-70%), and optimizing the pore size distribution (0.01-10 μm). These parameter adjustments enhance the mechanical properties and thermal stability while maintaining lithium ion conductivity, thus improving safety without sacrificing performance.
2Duration of action of stationary object
If a polymer separator is used in lithium secondary batteries, then the battery can operate with lithium ion transport, but the heat resistance is weak, limiting battery life
Solution Approach 1:
The ceramic-coated polyolefin composite structure provides superior heat resistance compared to pure polymer separators. The ceramic layers (alumina, silica, boehmite) maintain structural integrity at high temperatures, preventing separator collapse and maintaining pore structure for continuous lithium ion transport, thereby extending battery life under thermal stress.
Solution Approach 2:
The ceramic coating layers act as a protective barrier that cushions the polyolefin base layer against thermal degradation before it occurs. The coating prevents direct exposure to extreme temperatures, reducing polymer chain scission and oxidation, thus preserving the separator's mechanical properties and ion transport capabilities over extended periods.
3Reliability
If the separator structure is enhanced for safety, then heat resistance and mechanical strength improve, but the complexity of manufacturing increases
Solution Approach 1:
The patent utilizes porous ceramic materials with controlled pore structures that can be deposited on the polyolefin base layer through established coating techniques. The porous structure maintains lithium ion conductivity while providing mechanical reinforcement and thermal stability, achieving safety enhancement through material selection rather than complex structural design.
Solution Approach 2:
The ceramic coating is applied selectively to specific regions or surfaces of the polyolefin separator where enhancement is most needed, such as the surfaces facing the electrodes. This localized approach provides safety improvements at critical interfaces while minimizing the overall complexity and material usage compared to full-thickness composite structures.
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 improves the safety, life characteristics, and performance of lithium secondary batteries by stabilizing lithium ion transport and preventing lithium dendrite formation, leading to enhanced charging/discharging performance and extended battery life.
Implementation Method 1
the first coating layer includes a solid electrolyte... providing improved ion and electron conductivity
Implementation Method 2
the second coating layer includes a lithium compound... configured to suppress the infiltration of materials constituting the negative electrode into the first coating layer
Data Source
AI summary
Provided is a separator for a lithium secondary battery. The separator for the lithium secondary battery may include a separator substrate, a first coating layer on the separator substrate, and a second coating layer on the first coating layer, wherein the first coating layer includes a solid electrolyte, and the second coating layer includes a lithium compound.