Composite Battery Separator With Nanotube Electrolyte Layer
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Solution Overview
Problem
Current polyolefin separators in lithium-ion batteries suffer from low melting point, poor electrolyte wettability, and shrinkage leading to short circuits, which affect safety and performance.
Innovation Solution
A composite separator with an electrolyte layer containing inorganic nanotubes and solid electrolyte particles, having a volume fraction of through-pores of 0.2%-5%, enhances heat resistance, electrolyte wettability, and lithium-ion transport, reducing internal resistance and improving safety and cycle performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyolefin separator is used in lithium-ion batteries, then the separator provides basic separation function, but it has low melting point and poor electrolyte wettability leading to shrinkage and short circuits
Solution Approach 1:
The patent applies composite materials by coating the polyolefin separator with a composite layer containing inorganic particles (alumina, boehmite, silica), organic particles (PVDF, polyimide, aramid), and ceramic fibers. This composite structure combines the low-cost, good separation properties of polyolefin with the high heat resistance and electrolyte wettability of inorganic and ceramic materials, preventing shrinkage while maintaining separation function.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the separator by controlling the coating layer composition with specific weight ratios (inorganic particles 30-70 wt%, organic particles 5-60 wt%, ceramic fibers 5-60 wt%). This parameter optimization ensures the coating provides sufficient heat resistance and electrolyte affinity without excessive thickness that would impede lithium ion transport.
2Reliability
If a ceramic coating such as alumina or boehmite is provided on the polyolefin separator surface, then heat resistance and electrolyte wettability are improved, but lithium-ion transport performance decreases and internal resistance increases
Solution Approach 1:
The patent applies local quality by creating a multi-component coating layer where different materials perform specific functions: inorganic particles provide heat resistance and structural stability, organic particles enhance electrolyte wettability, and ceramic fibers provide mechanical strength and additional heat resistance. This localized functional distribution ensures high heat resistance without uniformly blocking lithium ion transport paths.
Solution Approach 2:
The patent utilizes porous materials by incorporating ceramic fibers and inorganic particles that form a porous network structure in the coating layer. This porous structure allows lithium ions to transport through the coating layer while the inorganic and ceramic components provide heat resistance, thus maintaining ion transport performance despite the presence of a thick coating.
3Object-affected harmful factors
If a thermoplastic resin coating such as PVDF, polyimide, or aramid is provided on the polyolefin separator, then electrolyte wettability is improved, but heat resistance and lithium-ion transport performance are compromised
Solution Approach 1:
The patent combines thermoplastic resin coatings with inorganic particles and ceramic fibers to create a composite coating layer. The thermoplastic resin (PVDF, polyimide, or aramid) provides excellent electrolyte wettability, while the inorganic particles and ceramic fibers contribute heat resistance and structural stability, compensating for the lower heat resistance of pure thermoplastic coatings.
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 composite separator improves safety, rate, and cycle performance of lithium-ion batteries by maintaining structural integrity and facilitating efficient lithium-ion transport, while reducing internal resistance.
Implementation Method 1
the electrolyte layer at least includes inorganic nanotubes and solid electrolyte particles... has excellent lithium-ion transport performance
Implementation Method 2
a volume fraction of through-pores of the inorganic nanotubes in the electrolyte layer is 0.2%-5%
Implementation Method 3
improve the heat resistance... The separator is prone to shrink during the use of the lithium-ion battery... causing the positive electrode and negative electrode to come into contact
Data Source
AI summary
The present application provides a composite separator and an application thereof. The composite separator includes a separator substrate and an electrolyte layer provided on at least one surface of the separator substrate. The electrolyte layer at least comprises inorganic nanotubes and solid electrolyte particles. A volume fraction of through-pores of the inorganic nanotubes in the electrolyte layer is 0.2%-5%. The composite separator not only has excellent heat resistance and electrolyte solution wettability, but also has excellent lithium-ion transport performance when applied to a battery, thereby reducing the internal resistance of the lithium-ion battery and improving the rate performance and cycle performance of the lithium-ion battery.