Fluorinated Current Collector for Lithium-Ion Battery Corrosion

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Solution Overview

Problem

Current current collectors in electrochemical devices, particularly aluminum-based ones, suffer from pitting corrosion when used in lithium-ion batteries, leading to efficiency losses and reduced device lifespan, with existing solutions either increasing electrolyte costs or using more expensive materials.

Innovation Solution

A current collector with an electro-active surface featuring linear or branched fluorinated carbon functional chains, specifically perfluoroalkyl aryl moieties, is applied to the metal support, enhancing corrosion resistance without modifying the electrolyte composition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If aluminum current collector is used in lithium-ion batteries with TFSI electrolyte, then electrical connection efficiency is maintained, but pitting corrosion occurs leading to reduced device lifespan

Engineering Contradiction:

Improvecorrosion resistanceVSAvoiddevice lifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent applies a composite coating structure consisting of a bottom layer (such as adhesive resin layer) and a top layer (such as fluorinated polymer layer or carbon-containing layer). This multi-layer composite structure provides both adhesion to the aluminum current collector and protection against pitting corrosion from TFSI electrolyte, thereby extending device lifespan while maintaining electrical conductivity.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent employs thin film coatings (typically 0.1-10 μm thick) on the aluminum current collector surface. These thin films act as protective barriers against corrosive electrolyte while maintaining flexibility and electrical conductivity, preventing pitting corrosion without significantly increasing device thickness or weight.

Inventive Principle:

Principle #30Flexible shells and thin films

2Reliability

If protective coating is applied to aluminum current collector surface, then corrosion resistance is improved, but manufacturing complexity and processing difficulty increase

Engineering Contradiction:

Improvecorrosion resistanceVSAvoidprocessing ease

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent introduces an intermediary adhesive resin layer between the aluminum current collector and the protective top layer. This intermediary layer facilitates bonding between the metal substrate and the coating material, enabling durable protective coatings to be applied to aluminum surfaces without requiring complex surface treatment or specialized manufacturing processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If thick protective coating is applied to current collector, then corrosion protection is enhanced, but electron passage efficiency and device performance deteriorate

Engineering Contradiction:

Improvecorrosion protectionVSAvoidelectron passage efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent optimizes the thickness parameter of the protective coating to fall within the range of 0.1-10 μm. This parameter optimization ensures sufficient corrosion protection while maintaining adequate electron conductivity. The patent also adjusts the compositional parameters of the coating materials to balance protective properties with electrical conductivity.

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

This approach significantly reduces pitting corrosion, extends device life, and maintains electron passage efficiency, while being cost-effective and easily processable, with the functionalized surface showing improved corrosion resistance and heat resistance up to 400°C.

Implementation Method 1

the electro-active surface with linear or branched fluorinated carbon functional chains, comprising perfluoroalkyl aryl moieties, in the form of a molecular layer which improves the corrosion resistance of said electro-active surface

Methodology Applied

Scientific EffectElectrochemical reactions:

Implementation Method 2

not impairing the passage of electrons between said electrode and its current collector

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3356580B1Electrochemical devices, with current collector having an increased resistance to corrosion

Publication Date: 2019.11.06 UNIV DE NANTES

Figure 1~5B
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AI summary

Electrochemical device or photo-electrochemical device comprising an electrolyte containing a bistriflimide anion, hereafter named as TFSI-, at least two electrodes, each of these electrodes being in contact with a current collector comprising a metal support characterized in that at least one electrode has a current collector the metal support of which comprises an electro-active surface which is functionalized with linear or branched fluorinated carbon chains, such as perfluoroalkyl chains, in the form of a molecular layer which improves the corrosion resistance of said functionalized surface compared to a non- functionalized surface, wherein not impairing the passage of electrons between said electrode and its current collector, the functionalized surface being at the interface between said electrode and its current collector.