Low-Acetamide Sodium Electrolyte Salt for Stable SEI Formation

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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 acetamide content, prepared through a simple and inexpensive process, which improves the stability of the SEI and enhances battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional electrolyte salts are used in Na-ion batteries, then the battery can operate, but the solid-electrolyte interface (SEI) becomes unstable and battery lifespan is reduced

Engineering Contradiction:

ImproveSEI stabilityVSAvoidbattery lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte salt by controlling acetamide content to specific ranges (0.1-1000 ppm, preferably 1-500 ppm) and using specific sodium salt compositions (NaFSI, NaTFSI) with controlled purity levels. This parameter optimization stabilizes the SEI formation and improves battery lifespan without requiring expensive raw materials like LiFSI

Inventive Principle:

Principle #35Parameter changes

2Reliability

If high-purity sodium salts are used to improve battery performance, then coulombic efficiency increases, but manufacturing cost increases due to expensive purification processes

Engineering Contradiction:

Improvecoulombic efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent identifies specific impurity level parameters that optimize performance without requiring complete purification. By controlling acetamide to 0.1-1000 ppm and allowing certain impurities (NaCl, NaF, NaFSO3) to remain below 1000-3000 ppm, the patent achieves high coulombic efficiency while avoiding costly ultra-purification steps, making the process economically viable

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive raw materials like LiFSI with cheaper sodium-based salts (NaFSI, NaTFSI) that can be manufactured through simpler, more cost-effective processes. The invention demonstrates that high performance can be achieved with these cheaper materials when their composition parameters are properly controlled

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Object-affected harmful factors

If environmentally friendly sodium-ion batteries are developed as alternatives to lithium-ion batteries, then environmental sustainability improves, but interface stability challenges arise

Engineering Contradiction:

Improveenvironmental sustainabilityVSAvoidinterface stability

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent optimizes the chemical parameters of sodium-based electrolyte salts, specifically controlling acetamide content and using specific anion compositions (bis(fluorosulfonyl)imide, bis(trifluoromethylsulfonyl)imide) with sodium cations. These parameter optimizations stabilize both the aluminum current collector passivation layer and the SEI at the electrode interfaces, resolving the reliability challenge while maintaining environmental sustainability

Inventive Principle:

Principle #35Parameter changes

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

The passivation layers formed during the first charge/discharge cycles of a battery are essential for battery lifespan. Passivation layers include in particular the passivation of aluminum, which is generally the current collector used at the cathode, and the solid-electrolyte interface (SEI), which is the inorganic and polymeric layer that is formed at the anode/electrolyte and cathode/electrolyte interfaces.

Methodology Applied

Scientific EffectSolid-electrolyte interface (SEI) formation:

Implementation Method 2

Methodology Applied

Scientific EffectPassivation layer formation:

Data Source

PatentUS20260062295A1Salt composition for low-acetamide-content electrolyte

Publication Date: 2026.03.05 ARKEMA FRANCE SA

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 an acetamide content of from 0.1 to 1000 ppm by weight. The invention also relates to a process for preparing this composition and to an electrolyte comprising same.