Bicyclophosphate Ionic Liquid Electrolytes for High-Voltage Li-Ion Safety

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Solution Overview

Problem

Lithium-ion batteries face safety challenges due to flammability and limited operating voltage, which restricts the extraction of capacity from Li-ion cathodes, and traditional electrolyte solvents have voltage stability issues, especially when used with high voltage cathodes.

Innovation Solution

An ionic liquid with a bicyclophosphate moiety is introduced as an electrolyte component in an aprotic organic solvent system, combined with metal salts and additives, to enhance thermal stability, conductivity, and flame retardancy, thereby extending voltage stability and improving battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional electrolyte solvents are used, then the battery can operate at normal conditions, but the voltage stability is insufficient and flammability occurs under abuse conditions

Engineering Contradiction:

Improvevoltage stabilityVSAvoidflammability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent employs composite electrolyte systems combining ionic liquids with conventional carbonate solvents (EC, DMF, DEC, EMC). This composite approach leverages the high voltage stability and non-flammability of ionic liquids while maintaining the good ionic conductivity and electrochemical window of carbonate solvents, thereby resolving the contradiction between voltage stability and flammability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical structure of ionic liquids by incorporating bicyclophosphate moieties into the cation structure. This structural parameter change enhances the thermal stability and flame retardancy of the electrolyte while maintaining its ionic conductivity and voltage stability, directly addressing the flammability issue without sacrificing reliability

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the operating voltage is extended to extract more capacity from Li-ion cathodes, then more energy can be stored, but the voltage stability of traditional electrolyte solvents deteriorates

Engineering Contradiction:

Improvecapacity extractionVSAvoidvoltage stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte by introducing ionic liquids with bicyclophosphate-containing cations. These structurally modified ionic liquids exhibit enhanced electrochemical stability and higher oxidation resistance, enabling the battery to operate at extended voltages (up to 4.5V or higher) without solvent decomposition, thus allowing greater capacity extraction from high-voltage cathodes

Inventive Principle:

Principle #35Parameter changes

3Reliability

If ionic liquids with bicyclophosphate moiety are introduced, then thermal stability and flame retardancy are improved, but the device complexity increases

Engineering Contradiction:

Improvethermal stabilityVSAvoidelectrolyte composition complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ionic liquids with bicyclophosphate moieties serve multiple functions simultaneously: they act as both the solvent medium and the flame retardant additive, while also providing high voltage stability and ionic conductivity. This multi-functionality reduces the need for separate additive packages and simplifies the overall electrolyte formulation despite the complex molecular structure

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 use of bicyclophosphate-based ionic liquids in lithium-ion batteries improves thermal stability, conductivity, and safety by reducing flammability and increasing voltage stability, allowing for higher capacity extraction from Li-ion cathodes.

Implementation Method 1

The use of bicyclophosphate-based ionic liquids in lithium-ion batteries improves thermal stability

Methodology Applied

Scientific EffectThermal stability:

Implementation Method 2

good room-temperature ionic conductivity

Methodology Applied

Scientific EffectIonic conductivity: Conduction (electrical)

Implementation Method 3

improve safety by reducing flammability

Methodology Applied

Scientific EffectFlame retardancy:

Implementation Method 4

a wide electrochemical window

Methodology Applied

Scientific EffectElectrochemical stability:

Data Source

PatentUS12155038B2Modified ionic liquids containing bicyclophosphate moiety

Publication Date: 2024.11.26 SIONIC ENERGY INC

AI summary

A bicyclophosphate-modified ionic liquid compound, the synthesis thereof, an electrochemical electrolyte containing a bicyclophosphate-modified ionic liquid compound, and energy storage device containing the electrolyte are disclosed.