Cathode Interlayer Composition for Low-Resistance Solid-State Batteries

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Solution Overview

Problem

Conventional Li-metal batteries face high interfacial resistance between the cathode and solid-state electrolyte due to the rigid nature of ceramic solid-state electrolytes, leading to limited contact area and poor Li-ion accessibility, resulting in low Li-ion conductivity, high impedance, and low current density.

Innovation Solution

An interlayer comprising a lithium salt and a sulfone compound, potentially within a polymeric matrix, is positioned between the cathode and the solid-state electrolyte to reduce interfacial resistance by providing continuous and uniform ion paths and increasing the viscosity of the interlayer, thereby reducing the mobility of the lithium salt and enhancing capacity retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a low melting compound (e.g., Li3BO3, Li2.3−xC0.7+xB0.3−xO3) is employed as a bonding material and Li-ion conductor, then the cathode/SSE interfacial resistance is lowered, but the Li-ion conductivity, current density, and impedance performance deteriorate at battery operating conditions

Engineering Contradiction:

Improvecathode/SSE interfacial resistanceVSAvoidLi-ion conductivity and current density

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent employs a composite interlayer comprising a polymeric matrix (providing mechanical flexibility and adhesion) combined with lithium salt (providing Li-ion conductivity). This composite structure overcomes the limitations of single-material approaches: the polymer ensures good contact with the rigid SSE while the lithium salt maintains high ionic conductivity, achieving both low interfacial resistance and high current density simultaneously

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the physical state parameter of the interlayer material from rigid (conventional bonding materials) to flexible (polymeric matrix with lithium salt). This parameter change allows the interlayer to conform to the surface morphology of both cathode and SSE, increasing effective contact area while maintaining high Li-ion conductivity through the polymer-lithium salt composite structure

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a rigid ceramic solid-state electrolyte is used, then safety and energy density are improved, but the contact area with cathode particles is limited due to rigid nature, leading to poor Li-ion accessibility

Engineering Contradiction:

Improvesafety and energy densityVSAvoidcontact area at cathode-SSE interface

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent introduces a polymeric matrix-based interlayer as an intermediary between the rigid ceramic SSE and the cathode particles. This intermediary material has flexible properties that enable it to conform to the irregular surfaces of both components, significantly increasing the effective contact area. The interlayer acts as a bridge that maintains good electrical and ionic contact while preserving the advantages of the rigid SSE

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent uses a polymeric matrix to create a flexible thin film interlayer that can adapt to the surface topology of cathode particles and the SSE interface. This flexible film structure overcomes the rigidity limitation of ceramic SSE, enabling intimate contact across large areas while maintaining the structural integrity and safety benefits of the solid-state electrolyte

Inventive Principle:

Principle #30Flexible shells and thin films

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 interlayer significantly reduces interfacial resistance by more than one order of magnitude, increases capacity retention, and extends the lifespan of the solid-state battery by minimizing corrosion and dendrite formation, while maintaining good ionic conductivity and thermal stability.

Implementation Method 1

the ability of the liquid electrolyte to conform to the first major surface of the cathode and/or a surface of the solid-state electrolyte

Methodology Applied

Scientific EffectWetting: Wetting

Implementation Method 2

the interlayer can comprise a polymeric matrix that can increase a viscosity of the interlayer and/or decrease a mobility of the lithium salt therein

Methodology Applied

Scientific EffectViscosity increase:

Data Source

PatentUS20240097114A1Interlayers for cathode/solid electrolyte interfaces in solid-state batteries and methods of making the same

Publication Date: 2024.03.21 CORNING INC

AI summary

Batteries include a current collector, a cathode, an interlayer disposed on the cathode, a solid-state electrolyte disposed on the interlayer, and a lithium anode disposed on the solid-state electrolyte. In aspects, the interlayer includes a lithium salt and a sulfone compound within a polymeric matrix. In aspects, the interlayer includes a lithium salt and a sulfone compound. In aspects, methods of forming a battery comprise disposing a precursor solution comprising a lithium salt, a sulfone compound, and a monomer on a first major surface of a cathode. Methods can further include curing the precursor solution to form an interlayer including the lithium salt and the sulfone compound within a polymeric matrix. In aspects, methods can include disposing a lithium salt and a sulfone compound on a first major surface of a cathode. Methods further include disposing a solid-state electrolyte over the first major surface of the cathode.