Sulfonated Elastomer Coating for Lithium Battery Cathode Stability

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Solution Overview

Problem

Current lithium-ion batteries face issues such as low energy density, inadequate cycle life, flammability, and safety concerns due to limitations in cathode active materials, including rapid capacity decay, thermal runaway, and electrolyte decomposition, primarily caused by transition metal catalysts and high oxygen content.

Innovation Solution

A cathode active material layer comprising particulates of cathode active materials encapsulated in a thin layer of sulfonated elastomer, which provides high elasticity, lithium ion conductivity, and electrical conductivity, preventing direct contact with the electrolyte and reducing undesirable chemical reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If transition metal oxide cathode active materials are used, then high energy density is achieved, but rapid capacity decay and electrolyte decomposition occur due to catalytic activity and high oxygen content

Engineering Contradiction:

Improveenergy densityVSAvoidcycle life

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

An elastomer coating layer is applied as an intermediary between the transition metal oxide cathode active material and the electrolyte. This coating prevents direct contact and catalytic reactions while maintaining lithium ion conductivity, thereby preserving both high energy density and improving cycle life by preventing electrolyte decomposition.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin elastomer film is used to coat the cathode active material particles. This flexible thin film provides mechanical protection, prevents particle aggregation, and maintains structural integrity during volume changes while allowing lithium ion transport, thus improving cycle life without sacrificing energy density.

Inventive Principle:

Principle #30Flexible shells and thin films

2Use of energy by moving object

If transition metal oxide cathode active materials are used, then high energy density is achieved, but thermal runaway and safety hazards increase due to high oxygen content

Engineering Contradiction:

Improveenergy densityVSAvoidthermal runaway risk

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The elastomer coating serves as a safety intermediary that physically separates the oxygen-rich cathode material from the electrolyte and anode. This prevents oxygen release and thermal runaway reactions while maintaining the high energy density benefits of transition metal oxide cathodes.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The elastomer coating transforms the potentially harmful high oxygen content and catalytic activity into benefits by using the coating material itself as a protective barrier that prevents thermal runaway while allowing the underlying cathode material to maintain its high energy density characteristics.

Inventive Principle:

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

3Reliability

If graphite anode is used instead of lithium metal, then safety concerns are reduced, but specific capacity and power density decrease

Engineering Contradiction:

ImprovesafetyVSAvoidspecific capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention changes the parameters of the cathode side by applying elastomer coating and using high-capacity transition metal oxide materials, which enables the system to achieve higher specific capacity and power density while maintaining safety through the protective coating, effectively pushing the boundaries of what is achievable with graphite anodes.

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 sulfonated elastomer-encapsulated cathode active material layer enhances cycle life, energy density, and safety by stabilizing the cathode structure, preventing electrolyte decomposition, and maintaining lithium ion conductivity, thus addressing the limitations of existing cathode materials.

Implementation Method 1

the encapsulating thin layer of sulfonated elastomer has a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 800%, and a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 2

the encapsulating thin layer of sulfonated elastomer has a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 800%

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10886528B2Protected particles of cathode active materials for lithium batteries

Publication Date: 2021.01.05 HONEYCOMB BATTERY CO

AI summary

Provided is a lithium battery cathode electrode comprising multiple particulates of a cathode active material, wherein at least a particulate comprises one or a plurality of particles of a cathode active material being encapsulated by a thin layer of a sulfonated elastomer, wherein the encapsulating thin layer of sulfonated elastomer has a thickness from 1 nm to 10 μm, a fully recoverable tensile strain from 2% to 800%, and a lithium ion conductivity from 10−7 S/cm to 5×10−2 S/cm. The encapsulating layer may further contain an electron-conducting additive and/or a lithium ion-conducting additive dispersed in the sulfonated elastomer.