Hydrate-Based Interlayer for Sodium Ion Battery Stability

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Solution Overview

Problem

Sodium-ion batteries face challenges with the instability of solid electrolytes against metallic sodium anodes, leading to dendritic growth and catastrophic failure, due to continuous decomposition and mixed-conducting interphase formation, which degrades long-term cycling performance.

Innovation Solution

A stable solid electrolyte interface is engineered using hydrate-based compounds like Na3SbS4·8H2O, forming a passivating layer that inhibits electronic transport and decomposition, allowing for high ionic conductivity and electronic insulation, thereby preventing interface growth and enhancing battery stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solid electrolyte material is used in contact with metallic sodium anode, then ionic conductivity is achieved, but decomposition occurs leading to mixed-conducting interphase formation and dendritic growth

Engineering Contradiction:

Improveinterface stabilityVSAvoidelectrolyte stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A passivation layer is introduced as an intermediary between the solid electrolyte material and the metallic sodium anode. This passivation layer prevents direct contact and decomposition reactions between the electrolyte and sodium metal, while still allowing ionic transport. The layer acts as a protective barrier that stabilizes the interface without blocking the essential electrochemical function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The battery interface is designed as a composite structure combining the solid electrolyte material with a passivation layer. This composite approach leverages the high ionic conductivity of the solid electrolyte while the passivation layer provides chemical stability and prevents decomposition. The combination resolves the contradiction by integrating materials with complementary properties.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If solid electrolyte material is used without passivation layer, then device complexity is reduced, but dendritic growth and catastrophic failure occur

Engineering Contradiction:

Improveinterface structureVSAvoidbattery safety

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The passivation layer is applied in advance to the solid electrolyte material before assembly with the sodium anode. This preliminary protective action prevents the harmful decomposition reactions and dendritic growth from occurring during battery operation. The anti-action is built into the structure beforehand, eliminating the need for complex monitoring or intervention systems.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If passivation layer is added to solid electrolyte, then interface stability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveinterface stabilityVSAvoidbattery assembly

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The passivation layer is formed on the solid electrolyte material in advance during the electrolyte preparation process. This preliminary action ensures that the protective layer is already in place before the electrolyte is assembled with the electrodes, simplifying the overall manufacturing process. The passivation step is integrated into the material preparation rather than being a separate post-assembly operation.

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 hydrate-coated solid electrolyte achieves a stable interface with sodium metal, delivering improved cycling performance and increased stability, with a smaller interfacial resistance and prolonged lifespan, even after extended use and rest periods.

Implementation Method 1

forming a passivating layer that inhibits electronic transport and decomposition

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

A stable solid electrolyte interface is engineered using hydrate-based compounds

Methodology Applied

Scientific EffectInterface formation:

Implementation Method 3

allowing for high ionic conductivity and electronic insulation

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 4

allowing for high ionic conductivity and electronic insulation

Methodology Applied

Scientific EffectElectronic insulation:

Implementation Method 5

preventing interface growth and enhancing battery stability

Methodology Applied

Scientific EffectDendrite inhibition:

Implementation Method 6

forming a passivating layer that inhibits electronic transport and decomposition

Methodology Applied

Scientific EffectPassivation:

Data Source

PatentUS11018372B2Interlayer sodium electrodes for sodium ion batteries

Publication Date: 2021.05.25 RGT UNIV OF CALIFORNIA

AI summary

A sodium-ion battery includes an electrode and a passivation layer on the electrode material.