Fiber-Reinforced Composite Separator for Solid-State Cells
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Solution Overview
Problem
Conventional electrochemical solid-state cells face mechanical instability and ion transport issues due to the limitations of porous plastic separators and polymer electrolytes, which can lead to short circuits and defects from lithium dendrites and foreign particles.
Innovation Solution
A fiber-reinforced composite material comprising a coherent, fibrous structure made of a polymeric material fully embedded with an ionically conductive polymer, providing enhanced mechanical stability and ion conductivity while preventing electrode contact, achieved by minimizing residual porosity and optimizing the volume fraction of the fibrous structure and ion-conductive polymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If porous plastic films are used as separators, then good permeability to electrolyte is achieved, but mechanical strength is limited and holes/cracks develop when lithium dendrites form
Solution Approach 1:
The invention uses a composite structure combining a porous plastic film separator with a mechanically stronger polymer electrolyte layer and reinforcing elements. The separator provides electrolyte permeability while the polymer electrolyte and reinforcing structures provide mechanical strength to prevent dendrite penetration and short circuits.
2Reliability
If polymer electrolytes are used to take over separator function, then electrode protection is improved, but mechanical stability deteriorates at elevated temperatures due to softening
Solution Approach 1:
The invention modifies the polymer electrolyte composition by adding reinforcing fibers and adjusting the polymer matrix properties to maintain mechanical stability at elevated temperatures. The composite structure allows the polymer electrolyte to provide electrode protection while the reinforcing elements prevent softening and creep at high temperatures.
3Quantity of substance
If polymer electrolyte is used as separator, then ion transport is enabled, but creep occurs at elevated temperatures leading to short circuits
Solution Approach 1:
The invention creates a composite polymer electrolyte system combining ion-conducting polymer matrix with mechanically reinforcing fibers. This composite structure maintains ion conductivity through the polymer matrix while the reinforcing fibers prevent creep and maintain structural integrity at elevated temperatures, thereby preventing short circuits.
4Strength
If continuous fibrous structure is embedded with ion-conducting polymer, then mechanical stability is increased, but porosity must be minimized which may affect ion transport
Solution Approach 1:
The invention applies different properties to different regions: the continuous fibrous structure provides mechanical stability and structural framework, while the ion-conducting polymer fills the pores and provides ion transport pathways. This local differentiation allows simultaneous optimization of mechanical stability and ion transport capability.
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 fiber-reinforced composite material significantly increases the mechanical stability of electrochemical solid-state cells, preventing short circuits and defects, while maintaining effective ion transport between electrodes, even at elevated temperatures.
Implementation Method 1
at least one ion-conducting polymer, wherein the at least one continuous, fibrous structure is embedded in the at least one ion-conducting polymer and pores comprising the at least one continuous, fibrous structure are substantially completely filled by the at least one ion-conducting polymer
Implementation Method 2
the fiber-reinforced composite material has a coating on at least one surface made of at least one material with a low surface energy of less than 72 mN/m
Data Source
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AI summary
The invention relates to a fiber-reinforced composite material (19) comprising at least one continuous, fiber-like structure (17) made of at least one polymeric material and at least one ion-conducting polymer, wherein the at least one continuous, fiber-like structure (17) is embedded in the at least one ion-conducting polymer and pores (18) comprising the at least one continuous, fiber-like structure (17) are substantially completely filled by the at least one ion-conducting polymer. The fiber-reinforced composite material (19) can advantageously be used in an electrochemical solid-state cell (1) for separating the electrodes (21, 22) from one another.