High-Dielectric Polymer Electrolytes for Ambient Li-Ion Conductivity
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Solution Overview
Problem
Conventional electrolytes for lithium-ion batteries face challenges such as flammability, safety concerns, and limited conductivity at ambient temperatures, which hinder their performance and reliability.
Innovation Solution
The development of high molecular weight functionalized polymers with high dielectric permittivity (>10) and low glass transition temperature (<−30° C.) is introduced. These polymers are produced through addition polymerization or anionic ring opening, followed by functionalization via Michael addition or nucleophilic substitution, to enhance their ion dissociation and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolytes are used in lithium-ion batteries, then the batteries can achieve basic ion conduction, but the electrolytes exhibit flammability and safety concerns
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by incorporating fluorinated cyclic carbonate components (specifically fluorinated 1,3-propanedione derivatives) into the electrolyte formulation. This chemical parameter modification reduces flammability while maintaining ion conduction capability, directly addressing the safety versus flammability contradiction.
Solution Approach 2:
The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate compounds with other electrolyte components (such as lithium salts and conventional carbonate solvents). This composite approach leverages the flame-retardant properties of the fluorinated compound while maintaining the electrochemical performance needed for battery operation, thus improving safety without sacrificing functionality.
2Reliability
If conventional polymer electrolytes are used, then ion conduction is achieved, but conductivity is limited at ambient temperatures
Solution Approach 1:
The patent modifies the physical and chemical parameters of the polymer electrolyte by introducing fluorinated cyclic carbonate components and adjusting the polymer structure. These parameter changes enable the electrolyte to maintain higher ionic conductivity at ambient temperatures by optimizing the balance between polymer chain flexibility and ion solvation 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 high dielectric polymers demonstrate improved ion transport and conductivity, leading to enhanced performance and safety in lithium-ion batteries, with the potential for broader application in electrochemical cells.
Implementation Method 1
The presently disclosed high molecular weight functionalized polymers have a relatively high dielectric permittivity (e.g., greater than 10) as well as a relatively low glass transition temperature (e.g., less than −30° C.). These properties present unique advantages when the polymer is used as a polymer electrolyte in an electrochemical cell, such as a lithium-ion battery. For example, the high dielectric constant of the material allows for strong dissociation of ions
Implementation Method 2
The glass transition temperature (Tg) of a polymer is indicative of the how easy or difficult it is for polymer chains within the structure to freely move around and is thus indicative of how easily ions can be transported through the structure. The glass transition temperature of amorphous polymers represents the temperature at which the polymer transitions from being stiff and brittle to being soft and rubbery. So, by lowering the glass transition temperature of the polymer, segmental motion is increased and hence the conductivity is increased.
Data Source
AI summary
High molecular weight functionalized polymers (“high dielectric polymers”) are disclosed herein, along with related methods of use and manufacture. The high dielectric polymers have a relatively high dielectric permittivity (e.g., greater than 10) as well as a relatively low glass transition temperature (e.g., less than −30° C.). The polymers may be produced utilizing addition polymerization or anionic ring opening to yield a linear or branched polymer backbone containing numerous residual nucleophiles. Then, nucleophilic substitution may be carried out to functionalize the residual nucleophiles. The functionalized polymer may then be purified and used as polymer electrolyte in an electrochemical cell (e.g., as nonaqueous polymeric electrolyte in a secondary Li-ion battery), if desired.