Multi-Nitrile Electrolyte for High-Voltage Lithium Battery Swelling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

High-voltage lithium secondary batteries face safety issues due to electrolyte oxidation and decomposition at high voltages, leading to swelling and reduced life cycle characteristics, especially during high-temperature storage and low-temperature discharge.

Innovation Solution

An electrolyte composition including a lithium salt, a non-aqueous organic solvent, and a multi-nitrile compound with specific structural features, along with additives like oxalatoborate and carbonate-based compounds, is used to suppress electrolyte decomposition and maintain battery performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a high voltage (4.4V system) is used to increase charge amount, then capacity density is improved, but electrolyte decomposition and safety problems worsen

Engineering Contradiction:

Improvecharge amountVSAvoidelectrolyte stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a multi-nitrile compound as an intermediary substance between the electrolyte and the high-voltage cathode. This compound acts as a mediator that forms a protective interface layer, preventing direct contact and reaction between the electrolyte and the high-voltage cathode material, thereby enabling stable operation at 4.4V without electrolyte decomposition

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical composition parameters of the electrolyte by adding a multi-nitrile compound with specific molecular structure (at least two nitrile groups). This parameter change modifies the electrochemical stability window and interfacial properties, allowing the system to operate at higher voltages without breakdown

Inventive Principle:

Principle #35Parameter changes

2Reliability

If aromatic compounds like biphenyl are added as redox shuttle additives to prevent thermal runaway, then safety is improved, but storage characteristics worsen due to gradual decomposition at high voltage

Engineering Contradiction:

ImprovesafetyVSAvoidstorage characteristics

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical structure parameter from aromatic compounds (biphenyl) to multi-nitrile compounds with aliphatic chains containing at least two nitrile groups. This structural parameter change results in better electrochemical stability and resistance to decomposition during storage while maintaining safety functions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system combining the multi-nitrile compound with lithium salt and non-aqueous organic solvent. This composite formulation provides synergistic effects where the multi-nitrile compound contributes to both safety (via redox shuttle mechanism) and long-term stability (via resistance to decomposition)

Inventive Principle:

Principle #40Composite materials

3Productivity

If continuous charge is performed to increase capacity utilization, then productivity is improved, but heat generation and safety deterioration worsen due to cathode structure collapse

Engineering Contradiction:

Improvecapacity utilizationVSAvoidheat generation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by having the multi-nitrile compound proactively form a protective interface layer on the cathode surface before any degradation can occur. This pre-formed protective layer prevents cathode structure collapse during continuous charging, thereby preventing the chain reaction that leads to heat generation and safety issues

Inventive Principle:

Principle #10Preliminary action

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 electrolyte significantly reduces battery swelling, maintains high-temperature storage and low-temperature discharge efficiency, and extends the life cycle of high-voltage lithium secondary batteries.

Implementation Method 1

an electrolyte for a high-voltage lithium secondary battery, which may not be oxidized and decomposed at the time of being kept at a high voltage

Methodology Applied

Scientific EffectElectrochemical stability:

Implementation Method 2

decrease a thickness increase rate of the battery through suppression of gas generation

Methodology Applied

Scientific EffectDecomposition reaction suppression:

Data Source

PatentUS9979049B2Electrolyte for lithium secondary battery and lithium secondary battery comprising same

Publication Date: 2018.05.22 SK ON CO LTD

AI summary

Provided are an electrolyte for a high-voltage lithium secondary battery and a high-voltage lithium secondary battery containing the same, and more particularly, an electrolyte for a high-voltage lithium secondary battery which may not be oxidized and decomposed at the time of being kept at a high voltage and a high temperature to prevent swelling of a battery through suppression of gas generation, thereby having excellent high-temperature storage characteristics and excellent discharge characteristics at a low temperature while decreasing a thickness increase rate of the battery, and a high-voltage lithium secondary battery containing the same.