Porous Aramid Nanofiber Separator for Lithium Dendrite Suppression
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Solution Overview
Problem
Conventional polyolefin-based separators in lithium secondary batteries suffer from issues such as dendrite formation, low coulombic efficiency, and safety concerns due to short circuits, which are not adequately addressed by existing solutions.
Innovation Solution
A porous aramid nanofiber film is developed through a method involving aramid nanoseed suspension formation, solvent exchange, and freeze-drying to create a film with mixed nano-micro pores, which is used as a separator in secondary batteries to enhance electrical and thermal stability and suppress dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin-based separator is used, then porosity and ionic conductivity are improved, but dendrite formation and short circuit occur
Solution Approach 1:
The patent employs a porous aramid nanofiber structure with controlled pore size distribution (micro-pores and nano-pores) to replace conventional polyolefin separators. The porous structure enables high ionic conductivity while the aramid material inherently suppresses dendrite formation through its chemical stability and pore architecture.
Solution Approach 2:
The invention uses composite aramid nanofiber structures combining different pore sizes (micro and nano) within a single separator material. This composite pore structure optimizes both ion transport pathways and dendrite suppression mechanisms, achieving superior performance compared to single-structure separators.
2Ease of manufacture
If conventional separator is used, then manufacturing simplicity is maintained, but battery lifespan and safety deteriorate
Solution Approach 1:
The patent changes the fundamental material parameter from polyolefin to aramid nanofiber, and transforms the pore structure parameters by creating a dual-scale porous system. These parameter changes enable both enhanced battery lifespan through dendrite suppression and compatibility with existing manufacturing processes.
3Reliability
If high porosity separator is used, then ionic conductivity increases, but mechanical strength decreases
Solution Approach 1:
The aramid nanofiber separator utilizes a carefully engineered porous structure where the nanofiber network provides mechanical reinforcement while the controlled porosity ensures ionic conductivity. The nanoscale fiber diameter creates a high surface area to volume ratio that maintains structural integrity even at high porosity levels.
Solution Approach 2:
The separator exhibits local quality variations with different pore sizes distributed throughout the structure. Micro-pores provide mechanical framework strength while nano-pores facilitate ion transport, creating local functional zones that simultaneously satisfy both mechanical and conductive requirements.
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 porous aramid nanofiber film exhibits improved electrical properties, high thermal stability, and low resistance, leading to increased battery lifespan and safety by inhibiting lithium dendrite growth and enabling high-speed charging and discharging.
Implementation Method 1
The suspension layer is immersed in an alcohol-containing protic solvent for first solvent exchange to prepare an aramid nanofiber film by self-assembly
Implementation Method 2
The aramid nanofiber film is immersed in water for second solvent exchange to form an aramid nanofiber hydrogel film
Implementation Method 3
Freeze-drying the aramid nanofiber hydrogel film to prepare a porous aramid nanofiber film
Implementation Method 4
increasing the ionic conductivity of lithium ions based on high porosity
Data Source
AI summary
A porous aramid nanofiber film, a manufacturing method thereof, and a secondary battery including the same are provided. The method of manufacturing the porous aramid nanofiber film includes forming an aramid nanoseed suspension layer by applying an aramid nanoseed suspension on a substrate. The suspension layer is immersed in an alcohol-containing protic solvent for first solvent exchange to prepare an aramid nanofiber film by self-assembly. The aramid nanofiber film is immersed in water for second solvent exchange to form an aramid nanofiber hydrogel film. Freeze-drying the aramid nanofiber hydrogel film to prepare a porous aramid nanofiber film.