NaFSI Electrolyte Salt Composition for Stable SEI in Sodium-Ion Batteries
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Solution Overview
Problem
Existing sodium-ion batteries face challenges in achieving long battery lifespan and stable passivation layers due to the instability of the solid-electrolyte interface (SEI) and current collector interfaces, and there is a need for a more environmentally friendly and cost-effective electrolyte composition.
Innovation Solution
A salt composition comprising a sodium cation and a bis(fluorosulfonyl)imide anion with controlled sulfamate ion content, prepared through a simple and inexpensive process, is used to enhance the stability of the SEI and improve battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte salts are used in sodium-ion batteries, then the battery can operate, but the solid-electrolyte interface (SEI) becomes unstable and battery lifespan is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte salt by controlling the sulfamate ion content to specifically 0.1-3000 ppm, which fundamentally alters the SEI formation characteristics and improves both SEI stability and battery lifespan
Solution Approach 2:
The patent replicates the successful electrolyte composition strategy from lithium-ion batteries (using LiFSI with controlled sulfamate content) and adapts it to sodium-ion batteries by using NaFSI with the same controlled sulfamate ion content range, thereby achieving similar performance improvements
2Reliability
If high-purity electrolyte salts are used to improve battery performance, then coulombic efficiency increases, but manufacturing costs increase due to expensive purification processes
Solution Approach 1:
The patent optimizes the sulfamate ion content parameter to a specific range (0.1-3000 ppm) that achieves high coulombic efficiency without requiring complete removal of sulfamate ions, thereby avoiding expensive multi-step purification processes while maintaining excellent battery performance
Solution Approach 2:
The patent accepts a controlled amount of sulfamate ion impurity (0.1-3000 ppm) rather than pursuing complete purification, effectively treating the sulfamate ions as a tolerable impurity that does not significantly impact performance but dramatically reduces manufacturing costs by simplifying the purification process
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 improves the coulombic efficiency and extends the battery lifespan by increasing the number of cycles while maintaining high performance at high charge and discharge rates, without using expensive raw materials like LiFSI.
Implementation Method 1
a composition comprising a salt composed of a sodium cation and an anion of formula (II)
Data Source
AI summary
The invention relates to a composition comprising a salt composed of a sodium cation and an anion of formula (II):wherein R1 and R2 independently represent a fluorine atom or a perfluorinated group, the composition having a sulfamate ion content of from 0.1 to 3000 ppm by weight. The invention also relates to a process for preparing this composition and to an electrolyte comprising same.