Solid Polymer Electrolyte Composition Balancing Conductivity and Strength
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Solution Overview
Problem
Conventional solid polymer electrolytes lack a combination of high mechanical properties and ionic conductivity, leading to dimensional instability and insufficient ionic conductivity in battery elements, particularly when used in lithium-metal batteries with pure alkaline metal anodes, where they can cause short-circuits and have limited applicability due to viscosity and crystallinity.
Innovation Solution
A polymerisable composition comprising a first polymer with a polyethylene oxide moiety, a photo-activable or heat-activable second moiety, a telechelic oligomer with end groups, and a lithium salt, which forms a solid polymer electrolyte through controlled polymerisation, enabling excellent ionic conductivity and mechanical stability, and is easier to apply and produce than existing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyethylene oxide-based solid polymer electrolyte is used, then ionic conductivity is improved, but mechanical stability deteriorates at temperatures above the melting point of PEO
Solution Approach 1:
The patent uses a block copolymer composite structure combining polyethylene oxide (PEO) blocks for ionic conductivity and polystyrene (PS) blocks for mechanical stability. The PEO segments provide ether-type coordination sites for lithium salt dissociation and flexible chains for ion transport, while the rigid PS blocks form a mechanically stable matrix that maintains structural integrity at temperatures above PEO's melting point.
Solution Approach 2:
The block copolymer creates local regions with different properties: PEO-rich domains provide ionic conduction pathways while PS-rich domains provide mechanical strength. This spatial separation of functions allows the material to simultaneously achieve high ionic conductivity and mechanical stability without requiring a uniform composition throughout.
2Stability of the object's composition
If the polymer chains have limited mobility to provide mechanical stability, then mechanical stability is improved, but ionic conductivity deteriorates
Solution Approach 1:
The block copolymer structure creates a composite where rigid PS blocks provide mechanical stability through limited chain mobility, while flexible PEO blocks maintain high chain mobility for ionic conduction. The micellar or phase-separated morphology allows PEO domains to move independently within the rigid PS matrix, decoupling the mechanical and ionic transport requirements.
3Reliability
If a solid polymer electrolyte is used to replace liquid electrolyte, then safety is improved, but contact with pure metal anode causes short-circuits
Solution Approach 1:
The block copolymer electrolyte combines the safety advantages of solid polymers with enhanced interfacial properties. The PEO segments provide good wetting and contact with the pure metal anode, preventing dendrite formation and short-circuits, while the solid polymer matrix eliminates electrolyte leakage and improves overall safety compared to liquid electrolytes.
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 a solid polymer electrolyte with enhanced ionic conductivity and mechanical stability, improving the service life and interface quality of battery elements, making them suitable for commercial use while being easier to manufacture and handle.
Implementation Method 1
The composition is polymerisable by the action of a radiation, preferably by the action of a UV radiation
Implementation Method 2
The second moiety is photo-activable and/or heat-activable
Implementation Method 3
The polyethylene oxide has ether-type coordination sites which enables the dissociation of the lithium salt and a flexible molecular chain which facilitates ion transport, such as lithium ions (Li+) transport
Data Source
AI summary
One aspect of the invention relates to a polymerisable composition for a solid polymer electrolyte comprising a first polymer comprising a first moiety capable of coordinating cations of an alkaline metal and/or of an alkaline-earth metal and a photo-activable and/or heat-activable second moiety, an oligomer having at least two photo-activable and/or heat-activable groups, a second polymer comprising a third moiety comprising a salt of an alkaline metal or of an alkaline-earth metal, a solvent, and a polymerisation initiator allowing initiating polymerisation between the second moiety of the first polymer and the photo-activable and/or heat-activable groups of the oligomer by the action of a temperature comprised between 20° C. and 150° C. or of a radiation. Other aspects of the invention relate to a solid polymer electrolyte obtained by polymerisation of the polymerisable composition of the invention, a battery element comprising the solid polymer electrolyte, and a method for producing a battery element comprising the solid polymer electrolyte.