Artificial Solid Electrolyte Interphase for Alkali Metal Batteries

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Solution Overview

Problem

Conventional solid electrolyte interphase (SEI) layers on alkali metal electrodes, particularly lithium (Li) electrodes, suffer from volume expansion, contraction, and dendrite formation, limiting the energy density and stability of Li-ion batteries.

Innovation Solution

A passivation layer comprising an alkali metal salt with a molar percentage of hydrogen ≤1% and a thickness ≥0.05 micrometers is formed by reacting an alkali metal with an inorganic gas, creating a homogeneous, thermally stable, and electronically insulating layer that prevents corrosion and reduces dendrite growth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional SEI layer is formed by immersing the electrode into the electrochemical cell containing solvent and cycling the cell, then the SEI layer is formed on the electrode, but the SEI layer suffers from volume expansion and contraction during cycling and is susceptible to dendrite formation

Engineering Contradiction:

Improvestability of SEI layerVSAvoidvolume stability of SEI layer

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the compositional parameters of the SEI layer by incorporating specific inorganic compounds (such as LiF, Li2SiO3, Li3PO4) with controlled ratios to replace organic components. This compositional transformation makes the SEI layer mechanically robust and resistant to volume changes during lithium ion insertion/extraction cycles, thereby resolving the contradiction between forming an SEI layer and maintaining its volume stability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite SEI layer structure combining inorganic compounds with specific organic components. The inorganic framework provides mechanical stability and volume resistance, while the organic components maintain ionic conductivity. This composite approach allows the SEI layer to simultaneously achieve structural integrity and electrochemical functionality, resolving the contradiction between stability and composition maintenance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a conventional SEI layer is formed on the electrode, then the electrode is passivated, but the electrode is susceptible to dendrite formation due to self-plating of Li onto itself along with uneven Li growth along the surface

Engineering Contradiction:

Improvepassivation effectivenessVSAvoiddendrite formation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition parameters of the SEI layer by incorporating inorganic compounds with specific lithium ion conductivity properties. This changes the transport characteristics within the SEI layer, enabling more uniform lithium ion flux distribution during cycling, which prevents localized lithium deposition and dendrite formation while maintaining effective passivation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The inorganic compounds in the SEI layer act as intermediaries that mediate lithium ion transport between the electrode and electrolyte. These inorganic components provide a stable pathways for lithium ion diffusion, preventing direct contact between lithium metal and electrolyte that would lead to uncontrolled plating and dendrite growth, thus resolving the contradiction between passivation and dendrite prevention.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If the energy density of Li-ion batteries is increased to be viable for electric vehicles or electrical power grids, then higher energy storage capacity is achieved, but the stability and dendrite formation issues of SEI layers limit the performance

Engineering Contradiction:

Improveenergy densityVSAvoidbattery stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent changes the compositional parameters of the SEI layer to include high比例的 inorganic compounds that provide superior mechanical and chemical stability. This allows the use of higher capacity electrodes (such as lithium metal or high-capacity alloys) without suffering from SEI layer degradation, thereby enabling higher energy density while maintaining battery stability over extended cycling.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary treatment to form a stable inorganic-rich SEI layer before the electrode is subjected to high-rate cycling or high-voltage operation. This pre-formed robust SEI layer serves as a protective barrier that prevents subsequent dendrite formation and electrode degradation, enabling the battery to operate at higher energy densities with improved long-term stability.

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 solution enhances the energy density and stability of alkali metal electrodes by reducing dendrite formation and improving the electrochemical performance, increasing the short-circuiting time of batteries and allowing for more efficient energy storage in Li-ion batteries.

Implementation Method 1

reacting a substrate comprising one or more alkali metals with a gas, and forming the passivation layer on at least a portion of the substrate, wherein the passivation layer comprises an alkali metal salt

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding