Li-Ion Electrolyte Additive for Stable Cathode Interfaces

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Solution Overview

Problem

Existing lithium-ion battery electrolytes suffer from instability at the cathode-electrolyte interface, leading to rapid interfacial impedance growth and capacity decay, which limits their ability to achieve high volumetric energy densities and long cycling life.

Innovation Solution

The use of an electrolyte fluid comprising at least 0.01 wt% of a specific additive, represented by Formula (I), which includes nitrile groups that stabilize the cathode interface and reduce anode overpotential, thereby enhancing battery longevity and fast charging capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional electrolytes are used, then high volumetric energy density can be achieved, but cathode structure instability and electrolyte degradation occur, leading to rapid interfacial impedance growth and capacity decay

Engineering Contradiction:

Improvevolumetric energy densityVSAvoidcathode structure stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent introduces a dual-function additive comprising a sultone group and a nitrile group as an intermediary substance between the cathode and electrolyte. The sultone group reacts with the cathode surface to form a stable protective layer, while the nitrile group coordinates with metal ions to stabilize the cathode structure. This intermediary additive prevents direct harmful interactions between the electrolyte and cathode, resolving the contradiction between achieving high energy density and maintaining cathode stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the chemical composition parameters of the electrolyte by incorporating specific dual-function additives with sultone and nitrile groups. This parameter change transforms the electrolyte's interaction characteristics with the cathode, enabling formation of stable interfacial layers and coordination with metal ions, thereby improving cathode structure stability without sacrificing volumetric energy density.

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If conventional electrolytes are used, then high volumetric energy density can be achieved, but interfacial impedance grows rapidly, leading to capacity decay

Engineering Contradiction:

Improvevolumetric energy densityVSAvoidinterfacial impedance growth

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by having the dual-function additive proactively form a stable protective interface layer on the cathode surface before harmful electrolyte degradation can occur. The sultone group reacts with the cathode surface to create a stable interfacial layer that prevents subsequent impedance growth, while the nitrile group provides ongoing stabilization. This preliminary protective action prevents the harmful interfacial impedance growth that would otherwise occur in conventional electrolytes.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If cathode surface coating is applied, then cathode material stability can be improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecathode material stabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the functions of cathode surface coating and electrolyte formulation into a single dual-function additive. Instead of requiring separate cathode coating and electrolyte modification processes, the additive combines both protective and stabilizing functions in one component that is simply added to the electrolyte. This merging eliminates the need for complex cathode coating manufacturing steps while achieving the same stability benefits.

Inventive Principle:

Principle #5Merging (Combining)

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 incorporation of the additive in the electrolyte fluid significantly improves the specific discharge capacity, reduces decay, and enhances round-trip efficiency of lithium-ion battery cells, especially under accelerated cycling conditions.

Implementation Method 1

The nitrile group coordinates with metal ions to stabilize the cathode structure

Methodology Applied

Scientific EffectCoordination:

Implementation Method 2

The sultone group reacts with the cathode surface to form a stable protective interface layer

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS20250167302A1Non-aqueous electrolyte and secondary battery comprising the same

Publication Date: 2025.05.22 APPLE INC

AI summary

This disclosure relates generally to battery cells, and more particularly, electrolyte additives for use in lithium-ion battery cells.