Polymer-Ceramic Composite Separator for Thermal Battery Design
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Solution Overview
Problem
Conventional thermal batteries face challenges with thick, fragile MgO powder separators that limit battery design and manufacturing efficiency, requiring high-pressure presses and expensive facilities, and suffer from low energy and power density due to the need for thick electrodes and electrolyte immobilization, which complicates handling and assembly.
Innovation Solution
The development of a flexible, porous polymer composite (PPC) film separator with a thin profile (0.3-1.2 mils thick) made from a combination of ceramic and thermoplastic, allowing for the use of a nitrate molten salt electrolyte, which enables thinner, more durable separators that can be tested and assembled efficiently, and supports up to 70% volume occupancy by the electrolyte, facilitating higher energy density and reduced thermal mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MgO pressed-powder separators are used, then temperature and chemical stability are obtained, but the separators become thick and fragile, limiting battery design and manufacturing efficiency
Solution Approach 1:
The patent applies composite materials by combining polymer matrix with ceramic particles to create a separator that integrates the thermal stability of ceramics with the flexibility and strength of polymers. This composite structure resolves the contradiction by providing both temperature/chemical stability and mechanical robustness, eliminating the fragility issue of pure MgO pressed-powder separators while maintaining the necessary stability properties.
Solution Approach 2:
The patent changes the material parameters by transitioning from traditional MgO pressed-powder to polymer-ceramic composite materials. This parameter change enables the separator to achieve optimal balance between thickness, strength, and stability, allowing thinner yet more durable separators that improve battery design flexibility and manufacturing efficiency.
2Reliability
If MgO pressed-powder separators are used, then electrolyte immobilization is achieved, but high-pressure presses and expensive facilities are required, increasing manufacturing complexity
Solution Approach 1:
The patent employs porous polymer-ceramic composite materials that provide effective electrolyte immobilization through their porous structure. The ceramic particles within the polymer matrix create a network that retains electrolyte effectively. This approach eliminates the need for high-pressure pressing operations and specialized facilities, significantly simplifying the manufacturing process while maintaining reliable electrolyte immobilization.
3Reliability
If thick electrodes and electrolyte immobilization are used, then chemical stability is maintained, but energy and power density are reduced
Solution Approach 1:
The patent uses polymer-ceramic composite separators that provide effective electrolyte immobilization with thinner construction compared to traditional MgO separators. This composite structure maintains chemical stability while reducing the thickness required for equivalent performance, thereby increasing the volume available for active materials and improving energy and power density.
4Power
If thin separator profile is used, then energy density is improved, but handling and assembly become more difficult
Solution Approach 1:
The patent implements flexible thin-film separators made from polymer-ceramic composites. The polymer matrix provides flexibility and mechanical strength, enabling the separator to be made thin for improved energy density while maintaining ease of handling and assembly. The flexible nature of the thin film allows for simple manipulation during manufacturing processes without the fragility issues of traditional thin ceramic 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
The PPC film separator enhances energy and power density, allows for more compact designs, reduces manufacturing costs, and enables safer and faster activation of thermal batteries with improved handling and assembly processes, while maintaining structural integrity and flexibility.
Implementation Method 1
allowing for the use of a nitrate molten salt electrolyte, which enables thinner, more durable separators that can be tested and assembled efficiently, and supports up to 70% volume occupancy by the electrolyte
Implementation Method 2
Thermal batteries are kept in an essentially frozen state until activated by heating. Within milliseconds of reaching operating temperature, thermal batteries produce very high pulse power outputs
Data Source
AI summary
A thin, flexible, porous polymer composite film useful as a separator for a molten-salt thermal battery having a lower temperature electrolyte melt formulation 150-250° C. typical of molten alkyl nitrate/nitrite comprises 5-50 weight percent of electrically non-conductive ceramic comprising a thermoplastic in the range of 50-95 weight percent. The high-surface-area ceramic is comprised of MgO (preferred), Al2O3, AlSiO2, BN, AlN, or a mixture of two or more of the foregoing; and providing a porous network having a porosity of not less than 30 percent by volume. Likewise, the electrodes can be manufactured with polymer-bonded particulates of porous ceramic such as MgO. Cells for thermal batteries are fabricated in the uncharged state, e.g., Carbon/lithiated metal oxide. Additionally, a polymer-based thermal battery construction can free design from the rigid stacked-pellet battery design. Alternatively, a porous ceramic composite film of MgO coated non-conductive ceramic fibers may be used as a separator.