Silicon Anode Battery Electrolyte for Gas Suppression

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Solution Overview

Problem

Lithium ion secondary batteries with carbonate-based solvents have low durability, leading to insufficient life characteristics and reduced battery capacity due to decomposition, and there is a need for improved rate characteristics and reduced gas generation.

Innovation Solution

A lithium ion secondary battery with a negative electrode comprising a silicon material and an electrolyte solution containing an open chain sulfone compound, a fluorinated cyclic carbonate, and an open chain carbonate, along with LiN(FSO2)2 as a supporting salt, which enhances battery characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If carbonate-based solvents are used in the electrolyte solution, then the battery can achieve basic electrochemical performance, but the durability is low and the battery capacity is gradually reduced due to decomposition

Engineering Contradiction:

Improvebattery durabilityVSAvoidbattery life

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent changes the chemical composition parameters of the electrolyte solvent by introducing fluorinated cyclic carbonate compounds with specific molecular structures and ratios. This parameter change transforms the electrolyte from a decomposition-prone carbonate-based system to a more stable fluorinated system, resolving the contradiction between basic electrochemical performance and long-term durability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite electrolyte system by combining fluorinated cyclic carbonate with other carbonate components in specific proportions. This composite approach maintains the beneficial electrochemical properties of carbonate solvents while adding the stability and durability characteristics of fluorinated compounds, thereby extending battery life without sacrificing performance.

Inventive Principle:

Principle #40Composite materials

2Productivity

If conventional electrolyte solvents are used, then the battery can operate, but gas generation occurs and rate characteristics are insufficient

Engineering Contradiction:

Improverate characteristicsVSAvoidgas generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent modifies the electrolyte composition parameters by incorporating fluorinated cyclic carbonate compounds with specific molecular weights and fluorine content. These parameter changes suppress gas generation reactions while enhancing ionic conductivity, thereby improving rate characteristics without the harmful side effects of conventional solvents.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If the battery capacity is increased, then energy density is improved, but deterioration caused by electrolyte solvent decomposition becomes a problem

Engineering Contradiction:

Improveenergy densityVSAvoidbattery performance stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The fluorinated cyclic carbonate acts as an intermediary substance that mediates between the high energy density requirements and performance stability needs. It forms stable interfacial films that prevent direct contact and decomposition reactions between the electrolyte and electrodes, allowing high capacity operation without deterioration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

By changing the electrolyte composition to include fluorinated compounds with specific physical and chemical parameters, the system achieves both high energy density and stable performance. The parameter changes in solvent structure and composition enable simultaneous optimization of capacity and reliability.

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 proposed battery configuration improves battery characteristics by increasing electrical conductivity, reducing gas generation, and maintaining high capacity retention even after repeated charge-discharge cycles, while also enhancing cycle and rate characteristics.

Implementation Method 1

LiN(FSO2)2 reacts with a positive electrode and/or a negative electrode to form a film on an electrode surface having an effect of preventing decomposition of an electrolyte solution

Methodology Applied

Scientific EffectFilm formation reaction: Deposition (physical)

Implementation Method 2

an electrolyte solution comprising an electrolyte solvent comprising an open chain sulfone compound, a fluorinated cyclic carbonate and an open chain carbonate

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS11581581B2Lithium ion secondary battery

Publication Date: 2023.02.14 NEC CORP

AI summary

A purpose of the present invention is to provide a lithium ion secondary battery having improved battery characteristics. The lithium ion secondary battery according to the present invention comprises a negative electrode comprising a negative electrode active material comprising a silicon material and an electrolyte solution comprising an electrolyte solvent comprising an open chain sulfone compound, a fluorinated cyclic carbonate and an open chain carbonate and a supporting salt comprising LiN(FSO2)2.