Lithium Metal Powder Stabilization via LiF Passivation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing lithium metal powders used in secondary batteries are prone to dendrite formation and instability, leading to unsafe conditions and limited storage life, especially when exposed to air with moderate to high moisture levels.

Innovation Solution

Passivating lithium metal powder with a thin, dense LiF layer formed by fluorination, which provides better protection and stability compared to CO2 passivation, allowing for improved storage life and safety in various applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lithium metal powder is passivated with CO2, then it provides some protection against oxidation, but it decays rapidly in humid environments and has limited storage life

Engineering Contradiction:

Improvestability of lithium metal powderVSAvoidstorage life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the chemical composition parameter of the passivation layer from CO2-based compounds (Li2CO3) to fluorine-based compounds (LiF, CF3SO3Li). This parameter change results in a passivation layer with lower solubility in water and better stability, directly resolving the contradiction between providing protection and maintaining long-term storage life in humid environments

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite passivation structure by combining lithium fluoride (LiF) with fluorinated organic compounds (CF3SO3Li). This composite material approach produces a passivation layer that is both chemically stable and provides long-term protection, achieving both reliability and extended storage life simultaneously

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium metal is used in secondary batteries, then high specific capacity is achieved, but dendrite formation occurs during cycling causing unsafe conditions

Engineering Contradiction:

Improvespecific capacityVSAvoidsafety during cycling

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies preliminary action by forming a stable passivation layer on the lithium metal surface before the lithium is incorporated into the battery. This pre-formed LiF-based passivation layer prevents dendrite formation during subsequent cycling, allowing the battery to achieve high specific capacity while maintaining safety throughout the cycling process

Inventive Principle:

Principle #10Preliminary action

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 LiF passivation layer significantly reduces decay rates and maintains lithium metal content, ensuring safer and more stable operation of lithium batteries, even in humid environments, thereby extending their storage life and maintaining high specific capacity during cycling.

Implementation Method 1

The lithium metal powder is passivated by fluorine or fluorine-containing compounds. Such a thin, dense, continuous LiF layer provides better passivation

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

because of the solubility LiF (i.e., 0.133 g in 100 g H2O at 25° C.) is about one order of magnitude lower than that of Li2CO3 (i.e., 1.29 g in 100 g H2O at 25° C.)

Methodology Applied

Scientific EffectSolubility difference:

Data Source

PatentUS7588623B2Stabilized lithium metal powder for li-ion application, composition and process

Publication Date: 2009.09.15 LIVENT USA CORP

AI summary

A method of stabilizing lithium metal powder is provided. The method includes the steps of heating lithium metal to a temperature above its melting point, agitating the molten lithium metal, and contacting the lithium metal with a fluorination agent to provide a stabilized lithium metal powder.