Li-Ion Battery Electrolyte Additives for Cyclability Without Lithium Plating

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Solution Overview

Problem

Lithium-ion secondary batteries face challenges in achieving superior battery characteristics, particularly in cyclability and preventing lithium metal precipitation on the negative electrode during charging, which affects their performance and lifespan.

Innovation Solution

Incorporating a specific electrolytic solution comprising a cyclic sulfuric acid ester compound, a cyclic ether compound, and a chain alkyl dinitrile compound, with a weight ratio of the cyclic sulfuric acid ester compound to the positive electrode active material ranging from 0.01 to 2, which forms a protective film that inhibits lithium-ion insertion and extraction, thereby suppressing decomposition reactions during charging and discharging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electrolytic solution includes conventional additives (nitrile compound, S═O group-containing compound, cyclic ether), then the cyclability characteristic is improved, but lithium metal precipitation occurs on the negative electrode during charging

Engineering Contradiction:

Improvecyclability characteristicVSAvoidlithium metal precipitation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a specific compound (Formula 1) with controlled structural parameters (n1=0-3, R1-R6 groups) and optimizes its concentration ratio (0.01-2 mg/mg relative to positive electrode active material) to achieve superior cyclability while preventing lithium metal precipitation, representing a parameter optimization approach

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electrolytic solution employs a composite formulation combining Formula (1) compound with cyclic ether (Formula 2) and chain alkyl dinitrile (Formula 3) compounds, where each component contributes specific functions: Formula (1) prevents lithium precipitation, cyclic ether enhances cyclability, and dinitrile compound stabilizes the electrolyte, achieving synergistic effects

Inventive Principle:

Principle #40Composite materials

2Reliability

If the weight ratio of cyclic sulfuric acid ester compound to positive electrode active material is increased, then the protective film formation is enhanced, but the battery capacity and performance deteriorate

Engineering Contradiction:

Improveprotective film stabilityVSAvoidbattery capacity

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent precisely optimizes the weight ratio parameter of Formula (1) compound to 0.01-2 mg/mg relative to positive electrode active material, finding the optimal balance where sufficient protective film forms without excessive consumption of lithium ions, thereby maintaining high battery capacity and performance

Inventive Principle:

Principle #35Parameter changes

3Duration of action of stationary object

If the electrolytic solution composition is modified to improve cyclability, then the battery lifespan is extended, but the decomposition reactions during charging and discharging increase

Engineering Contradiction:

Improvebattery lifespanVSAvoiddecomposition reactions

Core Design Contradiction:

Duration of action of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The Formula (1) compound acts as an intermediary substance that forms a stable protective film on the electrode surface, which mediates between the electrolytic solution and electrode, preventing direct harmful decomposition reactions while allowing beneficial lithium ion insertion and extraction, thus extending battery lifespan

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potential harmful effect of electrolyte decomposition into a beneficial protective mechanism by designing Formula (1) compound to preferentially react and form a stable protective film, which then prevents further decomposition reactions, effectively converting initial chemical reactivity into long-term stability

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

This configuration enhances the cyclability and overall battery characteristics by stabilizing the electrolytic solution and ensuring smooth lithium ion transfer, leading to improved capacity retention and extended battery life.

Implementation Method 1

forms a protective film that inhibits lithium-ion insertion and extraction

Methodology Applied

Scientific EffectFilm formation: Deposition (physical)

Implementation Method 2

the electrolytic solution includes a cyclic sulfuric acid ester compound... which forms a protective film

Methodology Applied

Scientific EffectAdsorption: Adsorption

Data Source

PatentUS12136703B2Lithium-ion secondary battery

Publication Date: 2024.11.05 MURATA MFG CO LTD

AI summary

A lithium-ion secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material. The electrolytic solution includes a cyclic sulfuric acid ester compound, a cyclic ether compound, and a chain alkyl dinitrile compound. A ratio of a weight (mg) of the cyclic sulfuric acid ester compound to a weight (g) of the positive electrode active material is from 0.01 to 2.