Nonaqueous Electrolyte Battery with Carbon Monoxide Mediator

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Solution Overview

Problem

Nonaqueous electrolyte lithium-ion secondary batteries experience self-discharge and decomposition reactions at high charge states, leading to gas generation, increased internal resistance, and capacity degradation due to oxidation and reduction reactions on the electrodes.

Innovation Solution

Incorporating a nonaqueous electrolyte with a specific ratio of carbon monoxide to difluorophosphoric acid and monofluorophosphoric acid, along with a titanium-containing oxide as the negative electrode material, to promote the circulation of carbon monoxide and suppress decomposition reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the battery is brought into a highly charged state, then the battery capacity is increased, but self-discharge and decomposition reactions occur on the electrode surfaces, generating gas and increasing internal resistance

Engineering Contradiction:

Improvebattery capacityVSAvoidgas generation

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

Carbon monoxide is introduced as an intermediary substance in the nonaqueous electrolyte. It mediates the electrochemical reactions by being oxidized at the positive electrode and reduced at the negative electrode, forming a circulation system that suppresses direct decomposition reactions of the electrolyte and prevents gas generation while maintaining high charge states

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition parameters of the nonaqueous electrolyte by adding carbon monoxide at specific concentrations (0.01-5% by mass) along with difluorophosphoric acid and monofluorophosphoric acid. This parameter modification alters the electrochemical behavior to suppress decomposition reactions and gas generation during high charge states

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If the battery is brought into a highly charged state, then the battery capacity is increased, but oxidation reaction on the positive electrode and reduction reaction on the negative electrode generate gas

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrolyte decomposition

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

Carbon monoxide serves as a mediator that undergoes controlled oxidation at the positive electrode and reduction at the negative electrode, providing an alternative reaction pathway that prevents direct electrolyte decomposition and reduces substance loss while enabling high charge states

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the potentially harmful oxidation and reduction reactions that cause electrolyte decomposition into a beneficial circulation system where carbon monoxide is repeatedly oxidized and reduced, transforming a harmful process into a protective mechanism that suppresses gas generation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Shape

If gas is generated in the battery, then the battery swells, but internal resistance increases and capacity decreases

Engineering Contradiction:

Improvebattery swellingVSAvoidbattery capacity

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

Carbon monoxide is preliminarily introduced into the nonaqueous electrolyte before battery operation to prevent gas generation. This preliminary action establishes a protective chemical environment that suppresses decomposition reactions and prevents the harmful sequence of swelling and increased internal resistance

Inventive Principle:

Principle #9Preliminary anti-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

This configuration effectively reduces gas generation and maintains battery capacity by controlling the oxidation reactions and internal resistance, even at high charge states.

Implementation Method 1

An oxidation reaction is caused on the surface of a positive electrode, which generates an oxidized gas (for example, carbon dioxide)

Methodology Applied

Scientific EffectOxidation reaction: Oxidation

Implementation Method 2

A reduction reaction is caused on the surface of a negative electrode, which generates a reduced gas (for example, hydrogen and carbon monoxide)

Methodology Applied

Scientific EffectReduction reaction: Reduction

Data Source

PatentEP2683006B1Nonaqueous electrolyte secondary battery and method for manufacturing the same

Publication Date: 2017.03.01 KK TOSHIBA

AI summary

According to one embodiment, there is provided a nonaqueous electrolyte secondary battery (1) including a positive electrode (4), a negative electrode (5) containing a titanium-containing oxide, and a nonaqueous electrolyte. The nonaqueous electrolyte contains carbon monoxide and at least one selected from difluorophosphoric acid and monofluorophosphoric acid. The ratio of the mass concentration of carbon monoxide to the sum of the mass concentrations of difluorophosphoric acid and monofluorophosphoric acid is in the range of 0.1 to 5%.