Linear Polymer Electrolyte for Solvent-Free Salt Dissociation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrochemical cells face challenges in achieving high cycle life and efficiency due to large molecule solvents that hinder continuous reactions at the electrode interface, and require solvents for salt dissociation, which affects safety and performance.
Innovation Solution
A polymer electrolyte with a high dipole moiety integrated into the backbone, combined with a low glass transition temperature moiety, enabling superionic conductivity without the need for solvents, using materials like allyl carbonate, PDADMA TFSI, and lithium salts, resulting in a high dielectric constant polymer electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large molecule solvents are used in electrochemical cells, then cycle life and efficiency are improved due to reduced diffusion and continuous reaction prevention, but vapor pressure increases leading to safety concerns
Solution Approach 1:
The patent changes the molecular weight parameter of the solvent from small (conventional) to large (≥5000 g/mol), which simultaneously reduces diffusion rates to prevent continuous reactions and lowers vapor pressure to improve safety. This parameter change resolves the contradiction by finding an optimal range that achieves both reliability improvement and harmful factor reduction.
2Reliability
If polymer materials with high dielectric constant are used to achieve 100% salt dissociation, then ionic conductivity is improved, but molecular mobility decreases due to high molecular weight
Solution Approach 1:
The patent optimizes the molecular weight parameter of the polymer solvent to a specific range (≥5000 g/mol) that provides sufficiently high dielectric constant for salt dissociation while maintaining adequate molecular mobility for ionic conduction. This parameter optimization resolves the contradiction between dissociation efficiency and mobility.
3Force
If high dipole molecules are added to low Tg polymers via side chains, then dielectric constant is improved, but device complexity increases due to multi-component composition
Solution Approach 1:
The patent merges the high dipole moment function and low Tg flexibility function into a single polymer chain structure, eliminating the need for separate high dipole additives and low Tg polymer matrices. This merging simplifies the composition from multi-component to single-component while maintaining both high dielectric constant and low glass transition temperature.
Solution Approach 2:
The patent creates a composite polymer structure within a single material that combines the properties of high dipole moment molecules and low Tg polymers, achieving the benefits of both without the complexity of multi-material composites. The single polymer contains both functional characteristics in its molecular structure.
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 polymer electrolyte achieves 100% salt dissociation and enhanced ionic conductivity, improving the cycle life and safety of electrochemical cells by eliminating the need for solvents and optimizing the combination of high dipole and low Tg moieties in the polymer backbone.
Implementation Method 1
The disclosed polymer electrolyte combines a superionic conductivity mechanism, where the high dipole moiety is in the backbone of the polymer
Implementation Method 2
A high dielectric material is helpful to achieving 100% or approximately 100% dissociation of the salts present in an electrochemical cell. The dielectric constant of the polymer electrolyte may greater than 10 or 20 at 10 k Hz
Implementation Method 3
A polymer electrolyte is disclosed that includes a polymer backbone that contains a high dipole moiety and a low Tg moiety. The low Tg moiety may have a Tg of less than 120° C.
Implementation Method 4
The disclosed polymers do not require the aid of solvents to dissociate salts (e.g., lithium salts). In select embodiments, the salt combined with the polymer may be a lithium salt, such as lithium hexafluorophosphate (LiPF6), LiClO4, LiBF4, LiAsF6
Data Source
AI summary
A polymer electrolyte is disclosed that includes a polymer backbone containing a high dipole moiety and a low Tg moiety and a salt combined with the polymer. In addition to other possible benefits, the high dipole moiety in the polymer backbone may improve the conductivity of the polymer electrolyte. Additionally, the combination of a moiety with a high dipole moment with a moiety to impart low Tg may result in a high dielectric constant (for example, greater than 10).