Phosphonium Solid Polymer Electrolyte for Room-Temperature Batteries
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Solution Overview
Problem
Solid polymer electrolytes for batteries have low room temperature conductivity and require higher operation temperatures for desired conductivities and energy densities, particularly in automotive applications, and are prone to metal dendrite formation and short-circuits.
Innovation Solution
A solid polymer electrolyte comprising a dissociable metal salt, a metal ion conductive polymer system, and a phosphonium salt with a specific formula, which is stable at room temperature and enhances ionic conductivity and stability, preventing dendrite formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid polymer electrolytes are used to replace liquid electrolytes, then safety is improved and flammability is reduced, but ionic conductivity at room temperature deteriorates and operation temperature must be increased
Solution Approach 1:
The patent creates a composite solid polymer electrolyte by combining polyethylene oxide (PEO) with phosphonium-based ionic liquid. This composite structure allows the material to maintain the safety advantages of solid polymers while incorporating the high ionic conductivity characteristics of ionic liquids, enabling operation at lower temperatures with improved performance.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the solid polymer electrolyte by selecting phosphonium salts with specific melting points below 100°C and incorporating them into the PEO matrix. This parameter optimization allows the electrolyte to achieve desired ionic conductivity at reduced operating temperatures while maintaining structural integrity.
2Reliability
If solid polymer electrolytes are used, then electrical isolation between electrodes is improved, but ionic conductivity at room temperature deteriorates
Solution Approach 1:
The composite structure combines the electrical isolation properties of solid PEO with the high ionic conductivity of phosphonium-based ionic liquid. The ionic liquid components provide mobile ions for conduction while the PEO matrix maintains physical separation and electrical isolation between electrodes.
Solution Approach 2:
The patent creates local regions of high ionic conductivity within the solid polymer matrix by incorporating phosphonium ionic liquid. These localized conductive pathways enable efficient ion transport while the overall solid structure maintains electrical isolation properties.
3Quantity of substance
If higher operation temperature is used to achieve desired conductivity, then ionic conductivity is improved, but energy density deteriorates due to increased thermal management requirements
Solution Approach 1:
The patent optimizes the composition parameters by incorporating phosphonium ionic liquid with melting point below 100°C, which enables the electrolyte to achieve high ionic conductivity at lower operating temperatures. This reduces or eliminates the need for external heating systems and thermal management infrastructure, thereby improving overall energy density.
4Ease of manufacture
If conventional solid polymer electrolytes are used, then manufacturing simplicity is maintained, but dendrite formation increases leading to short-circuits
Solution Approach 1:
The composite structure of PEO with phosphonium ionic liquid creates a more uniform ion distribution and smoother ion transport pathways. This composite morphology reduces localized stress concentrations and prevents dendrite nucleation, improving resistance to dendrite formation while maintaining manufacturing simplicity.
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 electrolyte provides improved ionic conductivity, increased energy density, and resistance to dendrite formation, enabling safer and more efficient battery operation over a wide temperature range.
Implementation Method 1
the dissociable metal salt is soluble in the metal ion conductive polymer system and the phosphonium salt
Implementation Method 2
the solid polymer electrolyte provides a transport medium for ions between the electrodes
Data Source
AI summary
Provided is a solid polymer electrolyte (SPE) comprising a dissociable metal salt; a metal ion conductive polymer system; and a phosphonium salt having the general formula [PR1R2R3R4]X, where each of R1, R2, R3 and R4 are independently selected from C1 to C12 hydrocarbons, which hydrocarbons may be optionally substituted by 1 to 5 heteroatoms selected from N, O, and S, and X is an anion. Further provided are a method for preparing the solid polymer electrolyte and an electrochemical cell comprising the solid polymer electrolyte.