Ceramic Battery Separator Resists Corrosive Electrolytes
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Solution Overview
Problem
Lithium-based batteries, particularly those in standby status for rapid deployment, face issues with downtime and limited lifetime due to the high cost and limited safety of existing separators like microporous polytetrafluoroethylene (PTFE) and glass fiber materials.
Innovation Solution
Development of high-quality, rollable ceramic separators (CeRollS) that are flexible, corrosion-resistant, and ion-permeable, designed to replace existing separators, with improved operational lifetime and reduced costs, by using tape casting and firing techniques to form Al2TiO5 and 3YSZ materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If microporous PTFE or glass fiber separators are used, then electrical isolation and ion permeability are achieved, but cost increases and lifetime is limited
Solution Approach 1:
The patent changes the material composition parameters by incorporating ceramic materials (alumina, silica) into the separator structure, transitioning from organic polymers to inorganic composites. This parameter change enables the separator to withstand higher temperatures and corrosive environments, extending lifetime while maintaining manufacturing feasibility through established ceramic processing techniques
Solution Approach 2:
The patent creates a composite separator structure combining ceramic particles (alumina, silica) with a porous matrix material. This composite approach leverages the thermal stability and chemical resistance of ceramics while maintaining the ion permeability properties of the porous structure, achieving both extended lifetime and cost-effectiveness
2Reliability
If PTFE separators are used, then ion permeability is maintained, but corrosion resistance to harsh electrolytes deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters by replacing organic PTFE with inorganic ceramic materials (alumina, silica) that possess inherent resistance to corrosive electrolytes. This parameter change transforms the separator's chemical stability, enabling it to withstand prolonged exposure to harsh battery electrolytes without degradation
Solution Approach 2:
The patent employs a ceramic coating layer applied to the separator surface, creating a protective barrier that sacrifices itself to protect the underlying structure from corrosion. This approach provides economical corrosion protection by using a thin, replaceable ceramic layer rather than requiring the entire separator to be made from expensive corrosion-resistant materials
3Reliability
If separator thickness is increased to improve safety, then reliability increases, but volumetric efficiency deteriorates
Solution Approach 1:
The patent uses composite ceramic-polymer structures where ceramic particles are distributed within a porous matrix. This composite architecture provides enhanced safety through the thermal stability of ceramics while maintaining thin overall thickness by leveraging the porous structure's ability to provide safety functions at reduced dimensions
Solution Approach 2:
The patent employs porous ceramic and ceramic-composite materials that provide safety functions (thermal runaway prevention, mechanical strength) through their porous architecture rather than through increased thickness. The porous structure allows ion transport while the ceramic framework provides thermal stability, achieving safety in thin separators
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
CeRollS separators demonstrate superior corrosion resistance, ion permeability, and electrical resistivity, extending battery life and reducing maintenance costs, while maintaining safety and reliability, even when exposed to harsh electrolytes like thionyl chloride and sulfuryl chloride.
Implementation Method 1
Demonstrated superior corrosion resistance to thionyl chloride, 12N hydrochloric acid (HCl) and sulfuryl chloride while two commercially available separator materials failed the same test
Implementation Method 2
Superior permeability characteristics demonstrated by better ionic permeability than commercial separator materials: Two different Al2TiO5 products produced as described herein showed an ion permeability of ̃1.16×10−15 cm2/sec. and ̃1.75×10−15 cm2/sec
Implementation Method 3
Enhanced electrical resistivity of >5.4×108 Ohm-cm. compared to literature limits of 1014 Ohm-cm
Data Source
AI summary
Methods for producing ceramic films Yttria Stabilized Zirconia (3YSZ) and aluminum titanate (Al2TiO5), and the physical properties of these films are described. The films produced have thicknesses and integrity suitable for handling and corrosion resistance to electrolytes, porosity, ion permeability and electrical resistivity suitable for use as separators between positive and negative layers for forming electrical batteries, particularly lithium batteries.