Nanoporous Battery Separator Coating for High-Temperature Stability
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Solution Overview
Problem
Existing lithium batteries face challenges in achieving high dimensional stability at elevated temperatures while requiring lower coating weights and thicknesses, which are necessary for reducing manufacturing costs and ensuring safety, especially in larger and higher energy density batteries.
Innovation Solution
A multilayer separator comprising a porous polymeric layer with nanoporous inorganic oxide/polymer composite layers on both sides, featuring a high volume fraction of organic polymer and small crystallite size inorganic oxide particles, provides enhanced thermal stability and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional inorganic oxide/polymer coating layers are used to provide dimensional stability at elevated temperatures, then thermal stability is improved, but coating weight and coating thickness increase, leading to higher manufacturing costs
Solution Approach 1:
The patent applies porous inorganic oxide particles with controlled pore structures to create a coating layer that provides thermal stability through the porous network architecture rather than material density. The pores allow for lower material content while maintaining structural integrity at elevated temperatures, thereby reducing coating weight while preserving dimensional stability.
Solution Approach 2:
The patent creates a composite coating layer combining inorganic oxide particles with polymer binder, where the synergistic interaction between the rigid porous inorganic framework and the flexible polymer matrix provides enhanced thermal stability at reduced material concentrations. The composite structure allows the inorganic phase to provide thermal resistance while the polymer provides cohesion, achieving dimensional stability with lower overall coating weight.
2Temperature
If conventional inorganic oxide/polymer coating layers are used to provide dimensional stability at elevated temperatures, then thermal stability is improved, but coating thickness increases, leading to higher manufacturing costs
Solution Approach 1:
The porous structure of the inorganic oxide particles creates a three-dimensional network that provides thermal stability through architectural design rather than material quantity. The interconnected pores allow the coating to maintain structural integrity at elevated temperatures with reduced thickness, as the porous framework resists collapse and deformation more effectively than dense materials of equivalent weight.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the coating system by using particles with specific pore size distributions, surface areas, and structural characteristics. These parameter changes enable the coating to achieve optimal thermal stability at minimal thickness by tuning the porous architecture to maximize thermal resistance per unit thickness.
3Reliability
If higher coating weights and thicknesses are used to ensure safety and dimensional stability, then reliability is improved, but manufacturing costs increase
Solution Approach 1:
The porous inorganic oxide particles provide high surface area and interconnected pore networks that enhance safety and dimensional stability functions at lower material concentrations. The porous structure facilitates electrolyte penetration and ion transport while maintaining mechanical integrity, allowing the coating to perform safety functions with reduced weight and thickness, thereby lowering material and manufacturing costs.
Solution Approach 2:
The composite formulation of inorganic oxide particles with polymer binder creates a synergistic system where the inorganic phase provides thermal and dimensional stability while the polymer provides adhesion and flexibility. This composite approach achieves reliable safety performance with optimized material usage, reducing the total coating weight required compared to conventional single-phase coatings, thus lowering manufacturing costs.
4Ease of manufacture
If lower coating weights and thicknesses are used to reduce manufacturing costs, then ease of manufacture is improved, but dimensional stability at elevated temperatures deteriorates
Solution Approach 1:
The porous inorganic oxide particles create a lightweight, thicknessefficient thermal stability mechanism where the pore network architecture provides structural reinforcement without requiring high material content. This allows the coating to maintain dimensional stability at elevated temperatures even at low weights and thicknesses, enabling cost-effective manufacturing without sacrificing thermal performance.
Solution Approach 2:
The composite coating system combines inorganic oxide particles with polymer binder in optimized ratios and configurations, creating a synergistic material system that achieves thermal stability with minimal material content. The composite structure allows the inorganic phase to provide thermal resistance while the polymer provides matrix continuity, enabling low-weight, low-thickness coatings that still deliver required dimensional stability.
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 achieves lower coating weights and thicknesses, improving dimensional stability and safety, while maintaining excellent ionic conductivity and reducing manufacturing costs.
Implementation Method 1
nanoporous inorganic oxide/polymer composite layers coated on both sides of the polymeric layer... provides enhanced thermal stability and ionic conductivity... provides increased dimensional stability at high temperature
Implementation Method 2
provides a high level of porosity for excellent ionic conductivity of the electrolyte in the pores of the separator
Data Source
AI summary
A separator for a lithium battery having (a) a porous polymeric layer, such as a polyethylene layer, and (b) a nanoporous inorganic particle/polymer layer on both sides of the polymeric layer, the nanoporous layer having an inorganic oxide and one or more polymers; the volume fraction of the polymers in the nanoporous layer is about 15% to about 50%, and the crystallite size of the inorganic oxide is 5 nm to 90 nm.