Composite SEI Layer for Silicon Anode Stability

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Solution Overview

Problem

Current lithium-ion batteries face issues with silicon-containing anode materials experiencing large volumetric expansion, leading to physical damage, capacity fade, and limited cycle life, while lithium metal batteries suffer from performance degradation and dendrite formation causing premature failure.

Innovation Solution

A method involving the application of a fluoropolymer via deposition to form a composite surface layer on lithium or silicon-based electroactive materials, creating a protective layer with lithium fluoride particles distributed in an organic matrix to enhance cycle stability and prevent dendrite growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If silicon-containing anode materials are used to achieve high specific capacity, then charge capacity is improved, but volumetric expansion causes physical damage and limited cycle life

Engineering Contradiction:

Improvecharge capacityVSAvoidcycle life

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A thin film coating comprising lithium fluoride particles distributed in an organic matrix material is applied to the surface of the silicon-containing anode material. This flexible thin film accommodates the volumetric expansion and contraction of silicon during lithium insertion/extraction cycles, preventing physical damage such as wrinkling, fracture, and cracking while maintaining structural integrity and electrical contact throughout cycling.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The protective coating is formulated as a composite material consisting of lithium fluoride particles dispersed within an organic matrix material. This composite structure combines the benefits of lithium fluoride (high mechanical strength, stability) with the organic matrix (flexibility, adaptability to volume changes), creating a coating that simultaneously protects against physical damage and accommodates volumetric expansion of the silicon anode.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium metal is used to achieve highest theoretical capacity, then energy density is improved, but dendrite formation causes premature cell failure

Engineering Contradiction:

Improvetheoretical capacityVSAvoiddendrite formation

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

A thin film coating comprising lithium fluoride particles distributed in an organic matrix material is applied to the surface of the lithium metal anode. This thin film acts as a protective barrier that suppresses dendrite formation by providing a uniform interface for lithium deposition, preventing the growth of branchlike metal structures that could puncture the separator and cause internal short circuits.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The coating comprising lithium fluoride particles in an organic matrix serves as an intermediary layer between the lithium metal anode and the electrolyte. This intermediate layer moderates the interaction between lithium metal and electrolyte species, preventing direct harmful reactions and guiding uniform lithium deposition, thereby eliminating dendrite formation while preserving the high theoretical capacity of lithium metal.

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 significantly improves the cycle stability and maintains charge capacity for over 500 hours, reducing mechanical stress and dendrite formation, thereby extending the lifespan and performance of lithium-ion batteries.

Implementation Method 1

The fluoropolymer reacts with lithium to form a composite surface layer on the one or more surface regions. The composite surface layer includes an organic matrix material having lithium fluoride particles distributed therein.

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

applying a fluoropolymer via a deposition process to one or more surface regions of an electroactive material

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

applying a fluoropolymer via a deposition process to one or more surface regions of an electroactive material

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS10497927B2Methods of applying self-forming artificial solid electrolyte interface (SEI) layer to stabilize cycle stability of electrodes in lithium batteries

Publication Date: 2019.12.03 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

A method of making a negative electrode for an electrochemical cell includes applying a fluoropolymer via a deposition process to one or more surface regions of an electroactive material. The electroactive material may be selected from the group consisting of: lithium metal, silicon metal, silicon-containing alloys, and combinations thereof. The fluoropolymer reacts with lithium to form a composite surface layer on the one or more surface regions that comprises an organic matrix material having lithium fluoride particles distributed therein. Electrochemical cells including such negative electrode are also provided.