Phosphonium Ionic Liquid Electrolyte for Wide-Temperature Stability

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Solution Overview

Problem

Existing ionic liquids lack stability over a wide temperature range and electrochemical stability, limiting their application in lithium secondary batteries, electrical double layer capacitors, fuel cells, and other energy storage devices.

Innovation Solution

Development of an ionic liquid with a phosphonium cation and specific anions, such as [(RfSO2)2N]-, [RFOO-], [RBF3]-, [N(CN)2]-, SO42-, HSO4-, and NO3-, which provides stability over a wide temperature range and low melting point, enabling its use as an electrolyte or reaction solvent in energy storage devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If ionic liquids with low viscosity and melting point (e.g., imidazolium system) are used, then ease of operation is improved, but stability deteriorates due to low reducing stability and narrow potential window

Engineering Contradiction:

Improveviscosity and melting pointVSAvoidstability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the cation type from imidazolium to phosphonium with specific P-N bonds, and adjusts the anion composition to achieve low melting point and viscosity while maintaining high stability and wide electrochemical potential window

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite ionic liquids by combining phosphonium cations with specific anions ([(RfSO2)2N]-, [RFOO]-, [RBF3]-, etc.) to achieve synergistic effects that simultaneously provide low viscosity, low melting point, and high stability

Inventive Principle:

Principle #40Composite materials

2Reliability

If ionic liquids stable over wide temperature range are used (e.g., ammonium cation), then stability is improved, but ease of operation deteriorates due to high melting point and viscosity

Engineering Contradiction:

Improvestability over temperature rangeVSAvoidmelting point and viscosity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the cation structure from ammonium to phosphonium with specific P-N bonds, which fundamentally alters the physical properties to achieve low melting point and viscosity while maintaining thermal stability

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If ionic liquids with low melting point are used, then ease of operation is improved, but stability deteriorates due to low thermal decomposition temperature

Engineering Contradiction:

Improvemelting pointVSAvoidthermal decomposition temperature

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent changes the cation type to phosphonium with specific P-N bonds and selects stable anions, which increases thermal decomposition temperature while maintaining low melting point

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent combines phosphonium cations with thermally stable anions to create composite ionic liquids that simultaneously achieve low melting point and high thermal stability

Inventive Principle:

Principle #40Composite materials

Data Source

PatentEP1956026B1Ionic liquid containing phosphonium cation having p-n bond and method for producing same

Publication Date: 2016.11.30 KANTO DENKA IND CO LTD

Figure 1~3

AI summary

An ionic liquid which contains an organic matter represented by the following general formula (1) as a cation component. The ionic liquid is stably in a liquid state over a wide temperature range and is excellent in electrochemical stability. The ionic liquid is advantageously used for applications such as electric power storage devices, lithium secondary batteries, electrical double layer capacitors, dye-sensitized solar cells, fuel cells, and reaction solvents.