Lithium Battery Cathode-Electrolyte Interface for High-Voltage Stability

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Solution Overview

Problem

Rechargeable lithium batteries face performance deterioration and safety issues due to electrolyte decomposition at high voltages and temperatures, leading to increased internal resistance and gas generation, which affects cycle-life and stability.

Innovation Solution

Incorporating a specific additive, represented by Chemical Formula 1, and carbon nanotubes in the electrolyte solution, along with a positive active material, to form a solid electrolyte interface that suppresses electrolyte decomposition and side reactions, thereby improving high-temperature stability and cycle-life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the voltage range is expanded to increase energy density, then the battery capacity is improved, but the positive electrode performance deteriorates due to electrolyte oxidization at high voltage

Engineering Contradiction:

Improvebattery capacityVSAvoidpositive electrode performance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A coating layer comprising at least one of a metal oxide, a metal hydroxide, a metal oxyhydroxide, or a metal carbonate is formed on the positive electrode surface. This coating layer acts as an intermediary barrier between the electrolyte and the positive electrode, preventing direct contact and thus suppressing oxidization reactions while allowing lithium ion transport, thereby maintaining electrode performance at high voltage

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The coating layer changes the surface properties of the positive electrode by introducing materials with different chemical stability characteristics. These parameter changes in surface composition and structure reduce the reactivity between the electrolyte and electrode, enabling stable operation at expanded voltage ranges

Inventive Principle:

Principle #35Parameter changes

2Reliability

If LiPF6 is used as the lithium salt in the electrolyte solution, then the ionic conductivity is improved, but the electrolyte decomposes at high temperature to generate gas and cause safety issues

Engineering Contradiction:

Improveionic conductivityVSAvoidelectrolyte decomposition and gas generation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The coating layer is formed on the positive electrode surface before the electrolyte can decompose and cause harmful effects. This preliminary protective barrier prevents the electrolyte from contacting the electrode surface, thereby preemptively stopping decomposition reactions and gas generation that would otherwise occur during high-temperature operation

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The coating layer transforms the potentially harmful interface between electrolyte and electrode into a beneficial protective barrier. By converting the harmful direct contact into a controlled interface through the coating layer, the system eliminates decomposition issues while preserving the ionic conductivity benefits of LiPF6

Inventive Principle:

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

3Speed

If the battery operates at high temperature, then the reaction rate is improved, but the side reaction is accelerated causing increased internal resistance and decreased stability

Engineering Contradiction:

Improvereaction rateVSAvoidbattery stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The coating layer serves as a thermal and chemical buffer between the electrolyte and the positive electrode. During high-temperature operation, this intermediary layer suppresses excessive side reactions by preventing direct electrolyte-electrode contact, thereby maintaining battery stability while still allowing beneficial reaction kinetics to occur

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively reduces gas generation and internal resistance, enhancing the battery's storage characteristics and cycle-life performance under high-temperature conditions.

Implementation Method 1

Methodology Applied

Scientific EffectSolid electrolyte interface formation:

Implementation Method 2

improving initial resistance and storage characteristics at a high temperature by improving impregnation of a positive electrode in the electrolyte solution

Methodology Applied

Scientific EffectImpregnation: Absorption (physical)

Data Source

PatentEP4142008B1Rechargeable lithium battery

Publication Date: 2026.03.11 SAMSUNG SDI CO LTD

Figure 1

AI summary

Provided is a rechargeable lithium battery including a positive electrode including a positive active material layer; a negative electrode including a negative active material layer; and an electrolyte solution including a nonaqueous organic solvent, a lithium salt, and an additive, wherein the positive active material layer includes a positive active material and carbon nanotube, the carbon nanotube is included in an amount of greater than 0.1 wt% and less than 3.0 wt% based on the total weight of the positive active material layer, and the additive includes a compound represented by Chemical Formula 1. Details of Chemical Formula 1 are as described in the specification.