Cathode Interface Coatings for Wider Solid-State Battery Voltage Windows

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Solution Overview

Problem

Solid state rechargeable batteries face a challenge due to the narrow thermodynamically stable interface voltage windows of solid electrolytes, which limits their operational lifetime when used outside these windows, and existing solutions have not effectively addressed this issue by finding suitable coating materials.

Innovation Solution

The use of specific compounds as cathode interface coating layers in solid state batteries, which provide enhanced dynamic stability and widen the operational voltage range by mechanical constriction, preventing interfacial decomposition reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If solid electrolytes are used outside their stable interface voltage windows, then the operational voltage range is expanded, but interfacial decomposition reactions occur that reduce operational lifetime

Engineering Contradiction:

Improveoperational voltage rangeVSAvoidoperational lifetime

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A coating layer comprising a compound from Table 1 is applied to the surface of the solid electrolyte particles. This coating acts as an intermediary between the solid electrolyte and the cathode, providing a protective interface that prevents decomposition reactions while enabling the battery to operate at higher voltages beyond the native stability window of the solid electrolyte.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the chemical composition and physical properties of the interface by applying a coating layer with specific characteristics (ionic conductivity, mechanical properties, electrochemical stability). This parameter change allows the interface to withstand higher voltages and prevent decomposition reactions that would otherwise occur in uncoated solid electrolytes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If coating materials are selected for thermodynamic stability within the desired operational voltage range, then interfacial decomposition is prevented, but few materials contain all desired characteristics for commercial batteries

Engineering Contradiction:

Improveinterfacial stabilityVSAvoidmaterial selection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention applies a coating layer with specific local properties (ionic conductivity, mechanical compliance, electrochemical stability) to the surface of the solid electrolyte particles. This localized modification provides the necessary interfacial stability without requiring the bulk solid electrolyte material itself to possess all desired characteristics, thus expanding material selection flexibility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention creates a composite structure consisting of the solid electrolyte core and a coating layer shell. This composite approach combines the high ionic conductivity of the solid electrolyte with the interfacial stability and voltage tolerance of the coating material, achieving a combination of properties that neither material possesses alone.

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If a coating layer is applied to the solid electrolyte particles, then dynamic voltage stability is enhanced, but the device complexity increases

Engineering Contradiction:

Improvedynamic voltage stabilityVSAvoidinterface structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The coating layer is applied in advance to the solid electrolyte particles before battery assembly. This preliminary action prevents interfacial decomposition reactions from occurring during initial battery operation, establishing stable interfaces beforehand and avoiding the formation of unstable reaction products that would complicate the interface structure.

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 proposed solution significantly enhances the dynamic voltage stability of solid state batteries, allowing them to operate within a wider voltage range and improve their cycling performance by stabilizing the cathode-electrolyte interface, thus extending the battery's operational lifetime.

Implementation Method 1

provide enhanced dynamic stability and widen the operational voltage range by mechanical constriction, preventing interfacial decomposition reactions

Methodology Applied

Scientific EffectMechanical constriction: Compression

Implementation Method 2

stabilizing the cathode-electrolyte interface, thus extending the battery's operational lifetime

Methodology Applied

Scientific EffectInterface stabilization: Adsorption

Data Source

PatentUS20250096276A1Cathode interface coating layers for solid state batteries

Publication Date: 2025.03.20 PRESIDENT & FELLOWS OF HARVARD COLLEGE

AI summary

The invention provides compounds that can be used as cathode interface coating layers in solid state batteries. The compounds disclosed herein provide enhanced dynamic stability.