Polymeric fluorinated gel electrolyte
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Solution Overview
Problem
Conventional gel polymer electrolytes used in solid-state batteries suffer from poor compatibility with anodes, leading to unfavorable solid electrolyte interphase (SEI) formation, which inhibits lithium ion intercalation and deintercalation, resulting in poor performance across various temperatures.
Innovation Solution
A polymeric gel electrolyte comprising a lithium salt with sulfur and fluorine, a lithium salt with boron, a fluorinated plasticizer, a non-fluorinated plasticizer, and a polymeric host, with a weight ratio of fluorinated to non-fluorinated plasticizer ranging from 9:1 to 1:9, is used to enhance lithium ion conduction and SEI formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional gel polymer electrolytes are used in solid-state batteries, then the electrolyte can be introduced to build favorable lithium ion conduction at the interface, but the electrolyte contributes to the formation of unfavorable solid electrolyte interphase (SEI) layer on the anode, which inhibits lithium ion intercalation and deintercalation
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing fluorinated plasticizers and specific lithium salts (LiTFSI, LiBF4) to modify the SEI layer properties. The fluorinated plasticizer content is controlled at 5-20 wt% of total plasticizer to optimize both conduction and SEI formation, transforming the harmful SEI layer into a beneficial protective layer that enables stable lithium ion intercalation and deintercalation
Solution Approach 2:
The patent creates a composite electrolyte system combining fluorinated plasticizer (e.g., FEC), non-fluorinated plasticizer (e.g., GBL), lithium salt including sulfur and fluorine (LiTFSI), and lithium salt including boron (LiBF4) in a polymeric host. This composite formulation synergistically improves lithium ion conduction while forming a stable, favorable SEI layer that prevents electrolyte decomposition and enables reversible lithium ion transport
2Adaptability or versatility
If conventional gel polymer electrolytes are used in solid-state batteries, then the battery can operate with solid-state electrodes, but the battery experiences poor performance across a range of temperatures, including poor room-temperature rate capability, poor low-temperature discharge, and poor high-temperature durability
Solution Approach 1:
The patent modifies the electrolyte's physical and chemical parameters by incorporating fluorinated plasticizers and optimizing plasticizer ratios to maintain appropriate viscosity and ionic conductivity across temperatures. The fluorinated plasticizer reduces viscosity at low temperatures while the specific lithium salt combination maintains stable ionic conductivity at high temperatures, enabling consistent performance from -40°C to 60°C
Solution Approach 2:
The composite electrolyte formulation combines multiple components with complementary temperature-dependent properties: fluorinated plasticizer (lowers freezing point and viscosity), non-fluorinated plasticizer (maintains flexibility), and dual lithium salts (ensure stable ionic conductivity). This composite system provides broad temperature adaptability while maintaining solid-state battery operation
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 proposed polymeric gel electrolyte improves the room-temperature rate capability, low-temperature discharge, and high-temperature durability of solid-state batteries, leading to enhanced battery performance across all climates.
Implementation Method 1
The electrolyte is suitable for conducting lithium ions between the electrodes
Implementation Method 2
a lithium salt including sulfur and fluorine, a lithium salt including boron
Data Source
AI summary
A polymeric gel electrolyte for an electrochemical cell, such as a solid-state battery, is provided herein as well an electrochemical cell including the polymeric gel electrolyte. The polymeric gel electrolyte includes a lithium salt comprising sulfur and fluorine, a lithium salt comprising boron, a fluorinated plasticizer, a non-fluorinated plasticizer, and a polymeric host. A w/w ratio of the fluorinated plasticizer to the non-fluorinated plasticizer is 9:1 to 1:9.