Multiblock Polyelectrolyte Electrolyte Balancing Conductivity and Stability
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Solution Overview
Problem
There is a need for a polyelectrolyte composition with improved ionic conductivity, mechanical, and electrochemical properties for next-generation lithium-ion batteries, which existing polyelectrolytes have not adequately addressed.
Innovation Solution
A polyelectrolyte composition comprising a polyionic multiblock polymer with a styrenic block copolymer precursor, a cross-linking agent, and an ionic liquid, specifically designed to enhance ionic conductivity and electrochemical stability, forming a conducting phase that can be processed into thin films for battery applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyelectrolytes are used in lithium-ion batteries, then electrochemical stability is improved, but ionic conductivity is insufficient
Solution Approach 1:
The patent uses a composite structure combining styrenic block copolymer (SBC) with ionic liquid (IL) and lithium salt to create a polyelectrolyte that achieves both electrochemical stability and high ionic conductivity. The SBC provides structural stability while the IL-Li salt complex provides ionic conduction pathways, resolving the contradiction between stability and conductivity.
Solution Approach 2:
The patent optimizes multiple parameters including the molecular weight of SBC blocks (10-100 kg/mol for block D, 5-100 kg/mol for block A), the ratio of ionic liquid to lithium salt (0.5-2.0 mL/mg), and the amount of cross-linking agent (0.05-20 mol%) to achieve the desired balance between electrochemical stability and ionic conductivity greater than 2.0×10⁻⁶ S cm⁻¹ at 30°C.
2Quantity of substance
If polyelectrolyte composition is optimized for ionic conductivity, then battery performance is improved, but mechanical properties may deteriorate
Solution Approach 1:
The patent introduces cross-linking at specific locations within the polyelectrolyte structure using cross-linking agents (0.05-20 mol% based on quaternary ammonium salt). This creates localized cross-linked regions that provide mechanical strength while maintaining the overall ionic conduction pathways through the polymer matrix, thus improving both mechanical properties and ionic conductivity simultaneously.
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 greater than 2.0×10−6 S cm−1 at 30°C and exhibits excellent discharge capacity and retention capacity, supporting the development of advanced lithium-ion batteries with improved performance.
Implementation Method 1
a film obtained from the polyelectrolyte composition has an ionic conductivity at 30° C. of greater than 2.0×10−6 S cm−1
Data Source
AI summary
A polyelectrolyte composition is disclosed comprising (a) a polyionic multiblock polymer (PILSBC) comprising a styrenic block copolymer (SBC) precursor having at least a quaternary ammonium salt; (b) a cross-linking agent comprising a compound having at least two amino groups; (c) a lithium salt; and (d) an ionic liquid. The SBC precursor comprises at least a block D derived from a substituted vinyl aromatic monomer; a block A derived from a vinyl aromatic monomer; and optionally a block B derived from a conjugated diene monomer. The polyelectrolyte composition has a mol ratio of the ionic liquid to the quaternary ammonium salt of 0.1:1-1:1. The polyelectrolyte composition provides improved ionic conductivity and electrochemical properties, and can be used in batteries, e.g., a Li-ion battery.