Fluorinated Sulfonamide Electrolyte for Lithium Dendrite Suppression
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Solution Overview
Problem
Traditional electrolyte solutions for lithium metal secondary batteries decompose easily, leading to lithium dendrite growth, which negatively impacts cycling and rate performance and safety, limiting their performance in applications like electric vehicles and aircraft.
Innovation Solution
An electrolyte solution comprising a fluorine-containing sulfonamide solvent with a specific structure, which reduces coordination with lithium ions and enhances anion coordination and ion conductivity, forming a dense interface film to inhibit dendrite growth and improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrolyte solutions are used in lithium metal secondary batteries, then the batteries can operate, but the electrolyte solutions decompose easily causing lithium dendrite growth, which deteriorates cycling performance, rate performance, and safety
Solution Approach 1:
The patent modifies the molecular structure of sulfonamide solvents by introducing fluorine atoms at specific positions (α-position or β-position) and adjusting alkyl group configurations. This changes the electronic properties and coordination ability of the solvent molecules with lithium ions, thereby improving electrolyte stability and preventing dendrite growth while maintaining good ion conductivity and battery performance
Solution Approach 2:
The patent employs composite electrolyte systems combining fluorine-containing sulfonamide solvents with lithium salts (such as LiFSO3, LiTFSO2, LiPF6) and optionally other carbonate or carboxylate solvents. This composite approach creates a synergistic effect where the fluorinated sulfonamide provides structural stability and dendrite inhibition, while the lithium salts ensure ionic conductivity, resolving the contradiction between stability and performance
2Speed
If the coordination ability of sulfonamide group with lithium ions is strengthened, then the ion conductivity improves, but the decomposition tendency increases leading to dendrite growth
Solution Approach 1:
The patent applies local quality modification by selectively introducing fluorine atoms at specific positions (α-position or β-position relative to the sulfonamide group) rather than uniformly throughout the molecule. This localized modification creates regions of different electronic properties: the fluorinated region provides electron-withdrawing effects that reduce overall coordination strength and prevent decomposition, while the sulfonamide region maintains sufficient coordination ability for good ion conductivity, thus resolving the contradiction between conductivity and stability
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 electrolyte solution enhances the rate and cycling performance of lithium metal secondary batteries by inhibiting dendrite growth, improving interface stability, and reducing corrosion, thereby enhancing safety and performance.
Implementation Method 1
the coordination ability of the entire fluorine-containing sulfonamide solvent with lithium ions is weaker than the coordination ability of anions in an inner layer solvation sheath structure of lithium ions
Implementation Method 2
This can particularly improve the coordination number of anions with lithium ions diffused to the electrolyte solution portion (i.e., the bulk phase electrolyte solution portion) at the electrode interface
Implementation Method 3
making the compound represented by formula (1) still have a higher donor number, thereby improving the ability to dissolve the electrolyte lithium salt
Data Source
AI summary
An electrolyte solution, a secondary battery, and an electrical apparatus. Components of the electrolyte solution include an electrolyte salt and a fluorine-containing sulfonamide solvent. The fluorine-containing sulfonamide solvent includes a compound represented by formula (1) in the disclosure, wherein T1 is selected from any one of the following formulas (1-1) to (1-3) in the disclosure: R1 and R2 are each independently selected from any one of alkyl having 1-3 carbon atoms, phenyl, and a sulfone group; T2 is fluorine-substituted alkyl group having 1-4 carbon atoms; and * represents a site of connection.