Single-Ion Polymer Electrolyte Gel for High-Conductivity Batteries
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Solution Overview
Problem
Existing polymer electrolytes for lithium-ion and sodium-ion batteries suffer from low cation transport numbers, concentration polarization, reduced electrochemical stability, and dendrite formation, limiting their application in high energy density batteries, while plasticizers used to enhance conductivity adversely affect mechanical properties.
Innovation Solution
A solid polymer electrolyte composition combining an organic polymer with tethered anionic groups and a metal salt dissolved in a solvent, achieving high ionic conductivity and cation transport numbers, along with exceptional mechanical strength, by using an organic polymer containing pendant groups with anionic moieties and a compatible metal salt in a solvent system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasticizer is added to improve ionic conductivity, then conductivity increases, but mechanical strength deteriorates
Solution Approach 1:
The patent uses a polymer matrix as an intermediary carrier to hold metal salts, replacing the traditional plasticizer approach. The polymer backbone provides mechanical strength while the metal salts provide ionic conductivity, with the polymer acting as a mediator that combines both functions without the adverse effects of small-molecule plasticizers.
Solution Approach 2:
The invention creates a composite material system consisting of polymer matrix, metal salts, and tethered anionic groups. This composite structure combines the mechanical properties of the polymer with the ionic conductivity of metal salts, achieving both high conductivity and mechanical strength simultaneously.
2Reliability
If conventional salt-in-polymer electrolyte is used, then ionic conductivity is achieved, but cation transport number decreases
Solution Approach 1:
The patent introduces tethered anionic groups at specific locations on the polymer chain to create localized regions that preferentially bind and transport cations. This local modification ensures that cations are selectively transported while anions remain immobilized, achieving high cation transport numbers.
Solution Approach 2:
The invention changes the fundamental parameter of ion mobility by tethering anionic groups to the polymer backbone, making them immobile. This parameter change forces the electrolyte to transport primarily cations, thereby increasing the cation transport number from below 0.5 to above 0.85.
3Quantity of substance
If single-ion conducting polymer electrolyte is used, then cation transport number increases, but ionic conductivity decreases
Solution Approach 1:
The patent merges the advantages of single-ion conductors (high cation transport number) with plasticized electrolytes (high conductivity) by combining polymer matrix, metal salts, and tethered anionic groups into a unified system that achieves both high conductivity and high cation transport number simultaneously.
Solution Approach 2:
The invention changes the conductivity parameter by introducing metal salts as additional charge carriers while maintaining the single-ion transport mechanism through tethered anionic groups. This dual approach increases ionic conductivity without sacrificing cation transport number.
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 composition achieves ionic conductivity comparable to liquid electrolytes, with cation transport numbers above 0.5, and maintains mechanical robustness, enabling the fabrication of thinner membranes for high energy density batteries.
Implementation Method 1
The number of freely moving charges is greatly increased within the polymer matrix while maintaining a high cation transport number
Implementation Method 2
a metal salt dissolved in the solvent in a molar concentration of 0.05 M to 1.5 M
Implementation Method 3
an organic polymer having a tethered anionic group along with a suitable concentration of a separate metal salt interacting with the polymer
Data Source
AI summary
A solid electrolyte composition comprising the following components: (i) an organic polymer comprising a polymeric backbone and pendant groups, wherein at least a portion of the pendant groups contain an anionic group associated with a first metal ion; (ii) a solvent homogeneously incorporated in the polymer to result in a polymer gel system; and (iii) a metal salt dissolved in the solvent in a molar concentration of 0.05 M to 1.5 M and containing a second metal ion associated with an anion, provided that the first and second metal ions are the same. Also described herein are solid-state batteries comprising: a) an anode; (b) a cathode; and (c) the solid electrolyte composition described above.