Tribochemical Barrier Layer for Alkali Metal Electrodes

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Solution Overview

Problem

Metallic lithium's limited application in secondary cells due to the formation of finely dispersed residues, such as dendritic and mossy lithium, which lead to battery capacity fade and potential internal shorts, necessitates the development of effective and cost-efficient protective barrier layers.

Innovation Solution

A tribochemical barrier layer is formed by bringing a barrier agent into frictional contact with an alkali metal substrate, using materials like Si, Li3N, or their combinations, to prevent residue formation while allowing electrochemical reactions, thereby enhancing the stability and efficiency of alkali metal electrodes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If metallic lithium is used as electrode material in secondary cells, then high electrochemical equivalent (3,884 Ah/g) and low electrode potential (3.05V) are achieved, but formation of finely dispersed residues (dendritic and mossy lithium) occurs leading to battery capacity fade and internal shorts

Engineering Contradiction:

Improveelectrochemical equivalentVSAvoidbattery safety and capacity stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A barrier layer is applied to the metallic lithium electrode surface before electrochemical cycling begins. This preliminary protective coating prevents direct contact between the lithium and electrolyte, thereby preventing the formation of dispersed residues during initial charge-discharge cycles and subsequent operation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A barrier layer material acts as an intermediary between the metallic lithium electrode and the electrolyte. This intermediate layer allows ionic transport while physically separating the lithium from direct electrolyte contact, preventing dendrite formation and internal short circuits while maintaining electrochemical performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If conventional barrier layers are formed by thermal deposition, magnetron sputtering, or chemical solution deposition, then protective coating is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:

Improveprotective barrier layer formationVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The barrier layer formation process utilizes the inherent properties of the barrier layer material and the electrode surface to enable spontaneous or self-driven coating formation. This self-service approach eliminates the need for complex external equipment such as thermal deposition chambers or magnetron sputtering systems, simplifying manufacturing while ensuring effective barrier layer formation.

Inventive Principle:

Principle #25Self-service

3Reliability

If conventional barrier layers are formed by vacuum sputtering or thermal deposition, then protective coating is achieved, but energy consumption increases

Engineering Contradiction:

Improveprotective barrier layer formationVSAvoidenergy consumption during barrier layer formation

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The invention replaces energy-intensive physical vapor deposition processes (thermal deposition, magnetron sputtering) with a mechanical friction-based approach. By using frictional contact between the barrier layer material and the electrode surface, the method achieves barrier layer formation through mechanical energy rather than thermal or electromagnetic fields, significantly reducing energy consumption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 tribochemical barrier layer effectively mitigates residue formation, improving the electrochemical performance and longevity of alkali metal electrodes by reducing overpotential and maintaining stable cycling, as demonstrated in lithium electrode tests.

Implementation Method 1

bringing a barrier agent into frictional contact with an alkali metal substrate to form a tribochemical barrier layer on the substrate

Methodology Applied

Scientific EffectTribochemical reaction: Tribocorrosion

Data Source

PatentUS20230052539A1Alkali metal materials

Publication Date: 2023.02.16 SIGMA LITHIUM

AI summary

There is disclosed a method of making a surface-modified alkali metal material for electrochemical use, the method comprising bringing a barrier agent into frictional contact with an alkali metal substrate to form a tribochemical barrier layer on the substrate. Also disclosed is a surface-modified alkali metal material for electrochemical use, the material comprising an alkali metal substrate bearing a tribochemical barrier layer.