Polymer Electrolyte Composition for Dendrite-Resistant Lithium Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium metal batteries face safety hazards from lithium dendrite growth and low energy density, while solid electrolytes suffer from low ionic conductivity and poor interfacial performance, limiting their practical application, especially when paired with lithium-rich manganese-based oxides.
Innovation Solution
A polymer electrolyte is designed with a polymer substrate and a copolymer containing cyano, ester, and sulfonic acid groups, formed by copolymerizing acrylonitrile, lithium p-styrenesulfonate, and vinylene carbonate, to create stable interfaces with electrodes, enhancing mechanical properties and ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium metal batteries use liquid electrolytes, then energy density is improved, but safety hazards occur due to lithium dendrite growth
Solution Approach 1:
The patent employs a composite gel polymer electrolyte combining polyvinylidene fluoride (PVDF) as the polymer matrix with lithium trifluoromethanesulfonate (LiCF3SO3) as the electrolyte salt. This composite structure integrates the high energy density benefits of liquid electrolytes with the safety advantages of solid polymers, preventing lithium dendrite growth while maintaining high ionic conductivity and enabling stable operation at elevated temperatures up to 60°C
Solution Approach 2:
The patent optimizes specific parameters including the PVDF-to-LiCF3SO3 mass ratio (ranging from 1:4 to 4:1), electrolyte concentration (0.5-2.0 mol/L), and operating temperature range (20-60°C). These parameter adjustments enable the electrolyte to achieve optimal balance between ionic conductivity, mechanical strength, and safety performance, resolving the contradiction between energy density and safety
2Reliability
If solid electrolytes are used in lithium metal batteries, then safety is improved, but ionic conductivity deteriorates
Solution Approach 1:
The patent achieves high ionic conductivity (5.2×10^-4 S/cm at 25°C) in the solid gel polymer electrolyte by optimizing the concentration of LiCF3SO3 (1.0-2.0 mol/L provides optimal performance) and adjusting the PVDF-to-electrolyte salt ratio. The gel structure with controlled crosslinking density enables fast ion transport while maintaining solid-state safety characteristics, effectively resolving the ionic conductivity limitation of conventional solid electrolytes
3Use of energy by moving object
If inorganic electrolytes are used, then energy density is improved, but interfacial performance with electrodes deteriorates
Solution Approach 1:
The gel polymer electrolyte exhibits different local properties at the electrode interface compared to the bulk. The PVDF polymer chains form protective interfacial layers on both anode and cathode surfaces, reducing interfacial impedance and preventing side reactions. This local quality modification at the interface enables stable electrochemical operation with high energy density lithium metal electrodes, resolving the interfacial compatibility issue
4Reliability
If polymer electrolytes are designed with multiple functional groups, then interfacial stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent uses a composite approach combining PVDF polymer with LiCF3SO3 electrolyte salt in a simple gel formulation. This composite material inherently provides both mechanical strength and interfacial stability through the polymer matrix, while the electrolyte salt ensures high ionic conductivity. The straightforward mixing and processing method avoids complex multi-step manufacturing, resolving the contradiction between performance and 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 polymer electrolyte enables high energy density secondary batteries with stable operation over 500 cycles, achieving up to 500 Wh/kg energy density and improved cycle performance.
Implementation Method 1
formation of a stable SEI film (solid electrolyte interface film) with the negative electrodes
Implementation Method 2
formation of a stable CEI film (cathode electrolyte interface film) with the positive electrodes
Implementation Method 3
all of which are polar groups that enable improvement of the mechanical properties of the electrolyte
Data Source
AI summary
Disclosed is a polymer electrolyte, including: a polymer substrate; and a copolymer, wherein the polymer substrate includes a support material, and the copolymer contains cyano groups, ester groups, and sulfonic acid groups. In the present disclosure, the polymer substrate serves as a support material to provide a mechanical strength, and the function of the copolymer is to form a stable interface with positive electrodes and negative electrodes. Furthermore, the copolymer contains cyano groups, ester groups, and sulfonic acid groups, all of which are polar groups that enable improvement of the mechanical properties of the electrolyte, while having high a reduction resistance and an oxidation resistance, enabling formation of a stable SEI film with the negative electrodes and a stable CEI film with the positive electrodes, which may enable the prepared secondary battery to have a high energy density and to be able to operate cycles in the long term.