Halogenated Cyclic Carbonate Electrolyte for Lithium Battery Safety

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Solution Overview

Problem

Lithium secondary batteries face safety issues due to oxidation of non-aqueous electrolyte solutions during high-temperature storage, leading to gas generation, swelling, and potential fires or explosions, with existing solutions either reducing battery capacity or causing phase separation and performance deterioration.

Innovation Solution

A non-aqueous electrolyte solution for lithium secondary batteries incorporating a halogenated cyclic carbonate, a vinylene or vinyl group-containing compound, and an alkoxyalkylnitrile compound, which form a passivation film to prevent thermal short circuits and oxidation reactions, thereby enhancing safety and preventing swelling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If porous polyolefin separators with high melting point are used to prevent fire at high temperature, then battery safety is improved, but film thickness must be increased which reduces the amount of anode and cathode and reduces battery capacity

Engineering Contradiction:

Improvebattery safetyVSAvoidbattery capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte solution by introducing a fluorinated cyclic carbonate compound with specific molecular structure (Formula 1) and controlling its concentration (5-20 wt%), which modifies the thermal and chemical stability parameters of the electrolyte to achieve fire prevention without requiring thicker separators

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate (Formula 1) with conventional cyclic carbonate (Formula 2) and chain carbonate (Formula 3) components, where the fluorinated compound forms a protective film that enhances safety while the conventional components maintain conductivity and capacity

Inventive Principle:

Principle #40Composite materials

2Temperature

If polyolefin separator is used, then high temperature resistance is improved, but the separator may be melted by drastic internal heat from electrolyte oxidation when overcharged causing internal short circuits

Engineering Contradiction:

Improvehigh temperature resistanceVSAvoidresistance to internal short circuit

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The fluorinated cyclic carbonate compound performs preliminary protective action by forming a stable surface film on the electrodes during normal operation, which prevents the drastic oxidation reactions that generate internal heat and overcharge conditions, thereby preventing separator melting before it can occur

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The patent modifies the electrochemical stability parameters of the electrolyte through the fluorinated compound, raising the oxidation potential and reducing the tendency for electrolyte decomposition and heat generation, thus protecting the separator from thermal damage

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If non-aqueous electrolyte solution is used to achieve high energy density, then battery energy density is improved, but the electrolyte is prone to oxidation during long-term storage at high temperatures generating gases and deforming battery structure

Engineering Contradiction:

Improveenergy densityVSAvoidelectrolyte stability

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical stability parameters of the electrolyte by introducing the fluorinated cyclic carbonate compound with strong C-F bonds, which has higher oxidation resistance and lower reactivity toward electrode materials, thereby suppressing gas-generating oxidation reactions during long-term high-temperature storage while maintaining the high energy density characteristics of non-aqueous electrolytes

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 solution effectively inhibits gas generation and heat generation, preventing battery swelling and ensuring safety during overcharge, while maintaining excellent charge/discharge performance and conductivity.

Implementation Method 1

incorporating a halogenated cyclic carbonate, a vinylene or vinyl group-containing compound, and an alkoxyalkylnitrile compound, which form a passivation film to prevent thermal short circuits and oxidation reactions

Methodology Applied

Scientific EffectPassivation film formation: Adsorption

Implementation Method 2

a non-aqueous electrolyte solution containing a lithium salt in a mixture of organic solvents

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Data Source

PatentUS8980481B2Non-aqueous electrolyte solution for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2015.03.17 LG ENERGY SOLUTION LTD

AI summary

Disclosed is a non-aqueous electrolyte solution for a lithium secondary battery. The non-aqueous electrolyte solution includes a lithium salt, an organic solvent and additives. The additives include: 1 to 10% by weight of a mixture of a particular halogenated cyclic carbonate and a compound containing a vinylene or vinyl group; and 0.1 to 9% by weight of a nitrile compound having a C2-C12 alkoxyalkyl group. A lithium secondary battery including the non-aqueous electrolyte solution is also disclosed. The lithium secondary battery is protected from catching fire when overcharged and is prevented from swelling during storage at high temperature.