NaSICON Ceramic Interface with Intermetallic Coating for Low-Temperature Sodium Batteries

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Solution Overview

Problem

Molten sodium batteries face limitations due to high operating temperatures, which result in poor wetting of molten sodium on NaSICON-type ceramics, leading to high interfacial resistance and reduced battery performance, especially at temperatures below 200°C, hindering widespread adoption.

Innovation Solution

Forming a sodium ion-conducting intermetallic phase on the surface of NaSICON-type ceramics, such as through coating with metals like tin, which forms a NaSn intermetallic phase, reducing interfacial resistance and enhancing sodium ion conduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If high operating temperatures (300-350°C) are used to achieve facile charge transfer between molten sodium anode and solid electrolyte separator, then charge transfer efficiency is improved, but battery longevity decreases, materials cost increases, and safety is compromised

Engineering Contradiction:

Improvecharge transfer efficiencyVSAvoidbattery longevity and safety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the operating temperature parameter from high (300-350°C) to low (below melting point of sodium, approximately below 98°C) by introducing a novel interface structure between the sodium anode and NaSICON electrolyte, enabling efficient charge transfer at temperatures previously considered too low for molten sodium battery operation

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary layer or modified interface structure between the molten sodium anode and the NaSICON solid electrolyte separator that facilitates charge transfer at low temperatures, acting as a mediator that enables efficient ion transport without requiring high thermal energy

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If temperature is lowered below 250°C to improve battery longevity and safety, then reliability is improved, but wetting of molten sodium on β''-Al2O3 separator deteriorates dramatically, increasing interfacial resistance

Engineering Contradiction:

Improvebattery longevityVSAvoidinterfacial resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material composition parameter of the separator or interface layer, transitioning from β''-Al2O3 to NaSICON-type ceramics, which exhibit superior low-temperature wetting properties and maintain low interfacial resistance at temperatures below 250°C

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material strategies by using NaSICON-type ceramics as the solid electrolyte separator, which combines ionic conductivity with excellent low-temperature wetting characteristics, creating a composite interface that simultaneously achieves low interfacial resistance and high reliability

Inventive Principle:

Principle #40Composite materials

3Reliability

If temperature is lowered below 200°C to enhance safety and longevity, then reliability is improved, but interfacial resistance increases due to poor wetting, reducing battery performance

Engineering Contradiction:

Improvebattery safetyVSAvoidbattery performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent changes the chemical composition parameter of the solid electrolyte from β''-Al2O3 to NaSICON-type ceramics, which fundamentally alter the interfacial interaction with molten sodium, enabling excellent wetting and low interfacial resistance at temperatures below 200°C while maintaining high ionic conductivity and safety

Inventive Principle:

Principle #35Parameter changes

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 intermetallic phase significantly decreases interfacial resistance and voltage requirements, enabling effective operation of molten sodium batteries at lower temperatures, thereby increasing battery longevity and safety, and improving overall performance.

Implementation Method 1

providing a sodium electrochemical interface with improved sodium ion conduction from a sodium source through the NaSICON-type ceramic

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

The intermetallic phase significantly decreases interfacial resistance and voltage requirements

Methodology Applied

Scientific EffectElectrical resistance reduction: Electrical Resistance

Data Source

PatentUS11545723B2Sodium electrochemical interfaces with NaSICON-type ceramics

Publication Date: 2023.01.03 NATIONAL TECHNOLOGY & ENGINEERING SOLUTIONS OF SANDIA LLC

AI summary

The present invention is directed to the modification of sodium electrochemical interfaces to improve performance of NaSICON-type ceramics in a variety of electrochemical applications. Enhanced mating of the separator-sodium interface by means of engineered coatings or other surface modifications results in lower interfacial resistance and higher performance at increased current densities, enabling the effective operation of molten sodium batteries and other electrochemical technologies at low and high temperatures.