Rechargeable Lithium Battery Electrolyte for High-Temperature Cycle Life

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Solution Overview

Problem

Rechargeable lithium batteries face challenges in maintaining high energy density and cycle-life characteristics, particularly at high temperatures, due to surface decomposition and resistance increases, which are not adequately addressed by existing electrolytes.

Innovation Solution

An electrolyte composition including a non-aqueous organic solvent, a lithium salt, and an additive compound represented by Chemical Formula 1, which forms a strong solid electrolyte interface (SEI) film on the negative electrode, reducing surface decomposition and resistance, and optimizing the additive's concentration for improved high-temperature performance and cycle-life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If conventional electrolytes are used to achieve high energy density, then battery capacity is improved, but resistance increase and surface decomposition occur at high temperatures

Engineering Contradiction:

Improveenergy densityVSAvoidhigh-temperature stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a novel additive compound with specific molecular structure (Formula 1) containing cyano group, alkenyl group, or alkynyl group that changes the chemical parameters of the electrolyte system. This additive modifies the SEI film composition and properties, enabling the battery to maintain both high energy density and high-temperature stability by controlling surface decomposition reactions through chemical parameter modification rather than physical parameter changes.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The additive compound acts as an intermediary substance between the electrolyte and the electrode surface. It mediates the interaction by forming a modified SEI film that prevents direct harmful contact between the electrolyte and electrode, thereby reducing surface decomposition and resistance increase while maintaining the high energy density functionality of the conventional electrolyte system.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If existing electrolyte compositions are used, then manufacturing simplicity is maintained, but cycle-life characteristics deteriorate due to surface decomposition

Engineering Contradiction:

Improveelectrolyte formulation simplicityVSAvoidcycle-life

Core Design Contradiction:

Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The patent modifies the electrolyte composition by incorporating a specific additive compound (Formula 1) at optimized concentrations (0.1-10 wt%, preferably 0.2-2.0 wt%). This parameter change in the chemical composition fundamentally alters the SEI film formation process, leading to improved cycle-life characteristics while maintaining the overall simplicity of the electrolyte formulation and manufacturing process.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If high energy density is pursued, then battery capacity increases, but resistance increase rates accelerate at high temperatures

Engineering Contradiction:

Improvebattery capacityVSAvoidresistance increase rate

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The additive compound serves as a protective intermediary that forms a stable interface layer between the electrolyte and electrode. This intermediary SEI film reduces the harmful resistance increase effects at high temperatures while preserving the high battery capacity functionality, effectively decoupling the relationship between energy density and resistance increase.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful surface decomposition reactions into a beneficial process by controlling the formation of a stable SEI film through the additive compound. The initial surface reactions that would normally cause degradation are redirected to form a protective layer that actually benefits long-term performance by preventing further decomposition and resistance increase.

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 proposed electrolyte composition significantly reduces resistance increase rates, enhances high-temperature stability, and improves cycle-life characteristics of rechargeable lithium batteries by forming a robust SEI film, thereby maintaining battery performance and safety.

Implementation Method 1

Methodology Applied

Scientific EffectSolid electrolyte interface (SEI) film formation:

Implementation Method 2

a positive electrode including a positive active material capable of intercalating/deintercalating lithium ions and a negative electrode including a negative active material capable of intercalating/deintercalating lithium ions

Methodology Applied

Scientific EffectIntercalation:

Data Source

PatentUS11908999B2Electrolyte for rechargeable lithium battery and rechargeable lithium battery

Publication Date: 2024.02.20 SAMSUNG SDI CO LTD

AI summary

An electrolyte for a rechargeable lithium battery and a rechargeable lithium battery including the electrolyte, the electrolyte including a non-aqueous organic solvent; a lithium salt; and an additive, wherein the additive includes a compound represented by Chemical Formula 1:in Chemical Formula 1, R1 is a cyano group, a substituted or unsubstituted C2 to C10 alkenyl group, or a substituted or unsubstituted C2 to C10 alkynyl group.