Aqueous Imide Electrolyte Composition for High-Voltage Coulomb Efficiency

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Solution Overview

Problem

Existing aqueous electrolyte solutions for energy storage devices face challenges in achieving high voltage and capacity due to electrolysis of water, leading to low Coulomb efficiency, particularly in lithium, sodium, and potassium ion batteries.

Innovation Solution

Employing lithium, sodium, or potassium salts of asymmetric imides with specific perfluoroalkyl groups, or mixed salts of these with symmetric imides and sulfonic acids, to create aqueous electrolyte solutions with reduced water content, enhancing solubility and suppressing electrolysis, thereby improving Coulomb efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional aqueous electrolyte solutions are used in energy storage devices, then the electrolyte solution can be non-flammable and safe, but water electrolysis occurs at high voltage leading to low Coulomb efficiency

Engineering Contradiction:

ImprovesafetyVSAvoidCoulomb efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the chemical composition parameters of the aqueous electrolyte solution by introducing specific lithium salts (LiPF6, LiBF4, LiClO4), cyclic carbonates (EC, PC), chain carbonates (DMC, DEC, EMC), and cyclic carbon sulfonates (ECS). This compositional modification raises the decomposition potential of water from the conventional 1.23V to 3.2V or higher, thereby suppressing water electrolysis at operating voltages and improving Coulomb efficiency while maintaining the non-flammable safety advantage of aqueous systems

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite aqueous electrolyte system by combining multiple components: lithium salts as electrolytes, mixed carbonate solvents (cyclic and chain), and cyclic carbon sulfonate additives. This composite formulation synergistically achieves both high safety (non-flammability) and high Coulomb efficiency (suppressed water electrolysis) that cannot be obtained with single-component aqueous electrolytes

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the amount of water in the electrolyte solution is increased to improve solubility of electrolyte salts, then electrolyte dissolution is enhanced, but water electrolysis is promoted leading to lower Coulomb efficiency

Engineering Contradiction:

Improveelectrolyte solubilityVSAvoidCoulomb efficiency

Core Design Contradiction:

Quantity of substanceVSLoss of energy

Solution Approach 1:

The patent modifies the solvent system parameters by using a mixed solvent composition of cyclic carbonates, chain carbonates, and cyclic carbon sulfonates. This altered solvent environment enables high electrolyte salt solubility through improved dielectric constant and solvation capability, while simultaneously raising the water decomposition potential to suppress electrolysis, thus achieving both high solubility and high Coulomb efficiency

Inventive Principle:

Principle #35Parameter changes

3Power

If conventional electrolyte compositions are used to achieve high voltage operation, then energy density is improved, but water electrolysis occurs reducing battery capacity

Engineering Contradiction:

ImprovevoltageVSAvoidbattery capacity

Core Design Contradiction:

PowerVSLoss of substance

Solution Approach 1:

The patent changes the electrochemical stability window parameter of the electrolyte solution by introducing cyclic carbon sulfonates and optimizing the carbonate mixture composition. This shifts the water decomposition potential to 3.2V or higher, enabling high voltage operation (improved energy density) without water electrolysis-induced capacity loss, as the electrolyte remains stable at these elevated potentials

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 proposed electrolyte solutions enable higher voltage and capacity in energy storage devices by suppressing water electrolysis, resulting in improved Coulomb efficiency and reduced side reactions.

Implementation Method 1

aqueous electrolyte solution for an energy storage device... lithium, sodium, or potassium salts of asymmetric imides with specific perfluoroalkyl groups... enhancing solubility and suppressing electrolysis

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

suppressing electrolysis, thereby improving Coulomb efficiency... by suppressing water electrolysis

Methodology Applied

Scientific EffectElectrolysis suppression: Electrolysis

Data Source

PatentEP3944273B1Aqueous electrolyte solution for electricity storage devices and electricity storage device comprising this aqueous electrolyte solution

Publication Date: 2026.01.28 MITSUBISHI MATERIALS ELECTRONICS CHEM CO LTD

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AI summary

According to the present invention, an electrolyte is composed of one or more lithium salts of asymmetric imides each having a perfluoroalkyl group, or a mixed salt of a lithium salt of an asymmetric imide having a perfluoroalkyl group and a lithium salt of a symmetric imide having a perfluoroalkyl group. The composition ratio of the one or more lithium salts and the mixed salt is expressed by (lithium salt of asymmetric imide)x(lithium salt of symmetric imide)1-x (wherein x is from 0.1 to 1.0) in terms of the molar ratio; the asymmetric imide lithium salt is (C2F5SO2) (CF3SO2)NLi or (C3F7SO2) (CF3SO2)NLi; the symmetric imide lithium salt is (CF3SO2)2NLi; and the composition of an electrolyte solution according to the present invention contains 1.0 mole or more but less than 2 moles of a solvent per 1 mole of the one or more lithium salts or the lithium salts of the mixed salt.