Non-aqueous Electrolyte Battery CO2 SEI Coating

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium ion secondary batteries face issues with gas generation and self-discharge due to carbon dioxide adsorption at the negative electrode, leading to increased internal pressure and reduced current performance, which is not effectively addressed by existing SEI coatings.

Innovation Solution

A non-aqueous electrolyte secondary battery design that incorporates a controlled amount of carbon dioxide in the active material layers, allowing for its release during heating, which suppresses gas generation and promotes suitable coating formation to reduce self-discharge, with specific ranges of carbon dioxide content and atmospheric conditions optimizing the balance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thick SEI coating is formed on the negative electrode active material, then the reaction between the active material and non-aqueous electrolyte is suppressed, but the diffusion resistance of lithium ion increases and large current performance is reduced

Engineering Contradiction:

Improvesuppression of reaction between active material and electrolyteVSAvoidlarge current performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameters of the SEI coating by controlling the amount of carbon dioxide (0.01-5% by volume) and water (0.01-5% by volume) in the atmosphere during electrode manufacturing. This results in an SEI coating with different chemical properties - specifically, one that is less prone to decompose and release gas while maintaining appropriate lithium ion diffusion characteristics.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If a thin SEI coating is formed on the negative electrode active material, then the diffusion resistance of lithium ion is reduced and large current performance is improved, but the reaction between the non-aqueous electrolyte and active material is less suppressed and self-discharge during storage increases

Engineering Contradiction:

Improvelarge current performanceVSAvoidsuppression of self-discharge during storage

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent modifies the SEI coating properties by controlling atmospheric parameters (carbon dioxide and water content) during electrode manufacturing. This creates an SEI coating that provides adequate protection against electrolyte reaction and self-discharge while maintaining sufficient lithium ion diffusion capability for good large current performance.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If carbon dioxide is adsorbed at the negative electrode, then it may react with the negative electrode active material, but this produces a large amount of gas and increases battery internal pressure

Engineering Contradiction:

Improvecarbon dioxide adsorptionVSAvoidgas generation and internal pressure increase

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent controls the amount of carbon dioxide in the atmosphere during electrode manufacturing (0.01-5% by volume) to regulate the amount of carbon dioxide adsorbed on the negative electrode active material. This prevents excessive gas generation during battery storage while ensuring sufficient carbon dioxide is present to form the desired SEI coating composition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potentially harmful effect of carbon dioxide adsorption (which could lead to gas generation) into a beneficial effect by controlling it to form an appropriate SEI coating. The controlled carbon dioxide adsorption helps create an SEI layer that is stable and less prone to decompose, thereby preventing the harmful gas generation that would otherwise occur.

Inventive Principle:

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

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 gas generation and self-discharge during storage while maintaining high rate performance by controlling carbon dioxide content and form in the active material layers, ensuring stable coating formation and reduced gas production.

Implementation Method 1

it is known that carbon dioxide is adsorbed as an impurity at the negative electrode

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

This coating is produced mainly due to the reductive decomposition of a non-aqueous electrolyte

Methodology Applied

Scientific EffectReductive decomposition: Reduction

Implementation Method 3

when the coating is too thick, diffusion resistance of the lithium ion becomes larger

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 4

At least one of the positive electrode active material layer and the negative electrode active material layer contains carbon dioxide and releases the carbon dioxide in the range of 0.1 ml to 10 ml per 1 g when heated at 350° C. for 1 minute

Methodology Applied

Scientific EffectThermal release: Heating

Data Source

PatentUSRE49306E1Non-aqueous electrolyte secondary battery

Publication Date: 2022.11.22 KK TOSHIBA

AI summary

According to one embodiment, there is provided a non-aqueous electrolyte secondary battery including a positive electrode including a positive electrode active material layer, a negative electrode including a negative electrode active material layer, and a non-aqueous electrolyte. At least one of the positive electrode active material layer and the negative electrode active material layer contains carbon dioxide and releases the carbon dioxide in the range of 0.1 ml to 10 ml per 1 g when heated at 350° C. for 1 minute.