Porous Ceramic Separator for Alkali Metal Ion Battery
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Solution Overview
Problem
Conventional alkali metal ion batteries face issues with separator failure due to lack of self-supporting integrity at high temperatures, leading to safety hazards such as fire and explosion, as polymeric separators melt and allow electrode intermixing, reducing Faradaic efficiency and battery capacity.
Innovation Solution
A porous ceramic alkali ionic conductor separator that is inert to liquid alkali ion solutions and maintains structural integrity at high temperatures, with a thickness of at least 200 μm and porosity between 20% to 70%, using materials like NaSICON-type or LiSICON-type ceramics, clad with ceramic or polymer membranes for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thin polymeric separator (2-3 microns) is used to enable high current density applications, then productivity is improved, but the separator lacks self-supporting integrity and melts at high temperature causing safety hazards
Solution Approach 1:
The patent employs a porous ceramic material (such as beta-alumina or NASICON-type ceramics) as the separator membrane. The porous structure allows ionic conduction while the ceramic material provides high temperature stability and self-supporting integrity, preventing the separator from melting during thermal runaway events.
Solution Approach 2:
The patent uses composite ceramic-polymer structures where a thin polymeric separator is coated with or combined with a ceramic layer. This composite structure maintains the thin profile for high current density while the ceramic component provides thermal stability and structural support at elevated temperatures.
2Reliability
If a thick ceramic separator is used to provide structural self-support and high temperature stability, then reliability is improved, but the separator thickness increases reducing current density capability
Solution Approach 1:
The porous structure of the ceramic separator reduces its effective thickness while maintaining mechanical strength and ionic conductivity. The interconnected pores allow ion transport pathways without requiring a thick solid barrier, thus achieving both structural integrity and high current density capability.
Solution Approach 2:
The patent optimizes the porosity, pore size distribution, and thickness parameters of the ceramic separator to achieve the desired balance. By controlling these parameters, the separator maintains sufficient mechanical strength for self-support while providing adequate ionic conductivity for high current density applications.
3Reliability
If a porous ceramic separator with 20-70% porosity is used to balance ionic conductivity and mechanical strength, then reliability is improved, but manufacturing precision becomes more challenging
Solution Approach 1:
The patent employs established ceramic processing techniques such as gel casting, slip casting, or extrusion followed by controlled sintering to create porous ceramic structures. These methods provide repeatable control over porosity (20-70%) and pore size distribution, achieving the desired balance between ionic conductivity and mechanical strength with consistent manufacturing precision.
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 ceramic separator provides structural self-support, prevents electrode mixing, and ensures safe operation at high temperatures, enhancing safety, power density, energy density, mechanical integrity, and thermal shock resistance while avoiding catastrophic failures.
Implementation Method 1
a porous and inert alkali ion conductive ceramic membrane
Implementation Method 2
maintains its structural integrity at high temperature
Implementation Method 3
The separator preferably has a porosity in the range from 20% to 70%
Implementation Method 4
selectively transports alkali ions, such as lithium and sodium ions
Data Source
AI summary
A separator for an alkali metal ion rechargeable battery includes a porous ceramic alkali ion conductive membrane which is inert to liquid alkali ion solution as well as anode and cathode materials. The porous ceramic separator is structurally self-supporting and maintains its structural integrity at high temperature. The ceramic separator may have a thickness of at least 200 μm and a porosity in the range from 20% to 70%. The separator may be in the form of a clad composite separator structure in which one or more layers of porous and inert ceramic or polymer membrane materials are clad to the alkali ion conductive membrane. The porous and inert alkali ion conductive ceramic membrane may comprise a NaSICON-type, LiSICON-type, or beta alumina material.