Lithium Battery Sulfone Electrolyte High Voltage Stability

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Solution Overview

Problem

Existing lithium ion secondary batteries face challenges in maintaining cycle charge/discharge characteristics, especially under high-voltage and high-temperature conditions, leading to a decrease in capacity.

Innovation Solution

A lithium ion secondary battery design incorporating a positive electrode with a sulfate group and an electrolyte solution comprising a sulfone compound, represented by Formula (1), which includes a cyclic or chain sulfone compound and a fluorinated ether, to enhance oxidation resistance and ion dissociation, thereby suppressing electrolyte decomposition and improving long-term cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbonate-based electrolyte solution is used, then cost is low and electrochemical resistance is excellent, but oxidation resistance is insufficient leading to electrolyte decomposition under high voltage

Engineering Contradiction:

Improveelectrolyte stabilityVSAvoidoxidation resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the chemical composition parameter of the electrolyte solvent from carbonate-based to sulfone-based (specifically cyclic sulfone compounds like sulfolane and gammaprolactone). This parameter change fundamentally alters the oxidation resistance properties, enabling the electrolyte to withstand high voltage conditions without decomposition while maintaining good electrochemical characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs a composite electrolyte system combining cyclic sulfone compounds with chain carbonates in specific proportions (cyclic sulfone: 10-70 vol%, chain carbonate: 30-90 vol%). This composite approach leverages the high oxidation resistance of sulfone compounds while utilizing the low viscosity and good ion conductivity of carbonate solvents, achieving balanced performance under high voltage conditions.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If high voltage operation is implemented, then energy density is improved, but electrolyte decomposition occurs leading to capacity loss

Engineering Contradiction:

Improveenergy densityVSAvoidcycle characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent raises the operating voltage parameter to achieve higher energy density, while simultaneously changing the electrolyte composition parameter to cyclic sulfone-based solutions that provide sufficient oxidation resistance at these elevated voltages, preventing decomposition and maintaining reliable cycle characteristics.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cyclic sulfone compound acts as an intermediary substance between the high voltage electrode reactions and the electrolyte stability requirement. Its high oxidation resistance property mediates the harsh high voltage conditions, preventing direct decomposition reactions and enabling sustained high-voltage operation with good cycle life.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Speed

If high temperature operation is implemented, then reaction kinetics are improved, but electrolyte decomposition accelerates

Engineering Contradiction:

Improvereaction kineticsVSAvoidelectrolyte stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent changes the electrolyte solvent type to cyclic sulfone compounds which possess inherent thermal stability. This parameter change allows the system to operate at elevated temperatures with improved reaction kinetics while the sulfone structure resists thermal decomposition, maintaining electrolyte stability that carbonate-based solutions cannot provide.

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 battery effectively suppresses electrolyte decomposition and maintains capacity retention under high-voltage and high-temperature conditions, improving the battery's long-term cycle performance.

Implementation Method 1

Cyclic carbonates have an effect of dissolving/dissociating lithium salts such as LiPF6 because of their high dielectric constant

Methodology Applied

Scientific EffectDissolution and dissociation: Solvation

Implementation Method 2

the incorporation of the sulfate group in the positive electrode facilitates the passage of electrons around particles

Methodology Applied

Scientific EffectElectron conduction: Conduction (electrical)

Implementation Method 3

chain carbonates have an effect of increasing diffusion of lithium ions in an electrolyte solution

Methodology Applied

Scientific EffectIon diffusion: Diffusion

Data Source

PatentUS9601809B2Lithium secondary battery

Publication Date: 2017.03.21 NEC CORP

AI summary

A lithium ion secondary battery which is a non-aqueous electrolyte secondary battery comprising a positive electrode comprising a positive electrode active material capable of absorbing and releasing lithium, and an electrolyte solution comprising a non-aqueous electrolyte solvent, wherein the positive electrode comprises a sulfate group, and the non-aqueous electrolyte solvent comprises a sulfone compound represented by a specified formula.