All-Solid-State Battery Cathode with Metal Fluoride Coating

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Solution Overview

Problem

In all-solid-state batteries, the electrochemical decomposition of sulfide-based solid electrolytes due to physical contact with conductive materials during charging and discharging leads to reduced lithium ion conductivity and battery deterioration, necessitating a solution to minimize this contact.

Innovation Solution

A cathode comprising a carbon-based material with a metal fluoride coating on its surface, which reduces the contact area with the solid electrolyte, using a combination of carbon-based materials like carbon fibers or nanotubes and metal fluorides such as MgF2, CaF2, or LiF, to suppress electrochemical reactions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a carbon-based conductive material is used in the cathode, then electron conductivity is improved, but physical contact with the solid electrolyte causes electrochemical decomposition and reduces lithium ion conductivity

Engineering Contradiction:

Improvebattery stabilityVSAvoidelectrochemical decomposition

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A sulfide layer is introduced as an intermediary between the carbon-based conductive material and the solid electrolyte. This sulfide layer acts as a protective barrier that prevents direct physical contact and electrochemical decomposition reactions, while still allowing lithium ion transport. The sulfide layer is formed in situ through reaction between the carbon-based material and the solid electrolyte during battery assembly or initial charging cycles.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The cathode structure is designed as a composite system comprising carbon-based conductive material, sulfide-based solid electrolyte, and a protective sulfide interface layer. This composite structure combines the high electron conductivity of carbon materials with the high lithium ion conductivity of sulfide electrolytes, while the interface layer resolves the incompatibility between these two materials.

Inventive Principle:

Principle #40Composite materials

2Object-generated harmful factors

If the contact area between conductive material and solid electrolyte is minimized, then electrochemical decomposition is suppressed, but electron conductivity in the cathode may be reduced

Engineering Contradiction:

Improveelectrochemical decompositionVSAvoidelectron conductivity

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The cathode structure is designed with spatially differentiated zones: regions where carbon-based conductive material directly contacts the cathode active material for efficient electron transfer, and regions where a sulfide protective layer intervenes between the carbon material and solid electrolyte to prevent decomposition. This local quality differentiation allows simultaneous optimization of electron conductivity and electrochemical stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The interface between conductive material and solid electrolyte is segmented into multiple functional zones: a direct contact zone for electron transfer, a sulfide layer formation zone for protection, and a transition zone. This segmentation allows different regions to perform different functions, maintaining electron conductivity while preventing harmful electrochemical reactions.

Inventive Principle:

Principle #1Segmentation

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

This configuration enhances the stability and cycle performance of the battery by minimizing electrochemical decomposition, maintaining high lithium ion conductivity and improving charging and discharging efficiency.

Implementation Method 1

a metal fluoride disposed on the surface of the carbon-based material... minimizes physical contact between a solid electrolyte and a conductive material

Methodology Applied

Scientific EffectPhysical barrier effect:

Implementation Method 2

Solid electrolytes conducts lithium ions between a cathode and an anode based on the high lithium ion conductivity thereof

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

electrons move through the conductive material

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 4

an oxidation reaction occurs at the interface, leading to electrochemical decomposition of the solid electrolyte

Methodology Applied

Scientific EffectOxidation reaction: Oxidation

Data Source

PatentUS20230238538A1Cathode for all-solid-state battery comprising conductive material composite and method of manufacturing the same

Publication Date: 2023.07.27 HYUNDAI MOTOR CO LTD

AI summary

A cathode for an all-solid-state battery includes a conductive material wherein the conductive material includes a carbon-based material and a metal fluoride disposed on the surface of the carbon-based material, and a method of manufacturing the same. The cathode for an all-solid-state battery includes a cathode active material, a solid electrolyte, and a conductive material, wherein the conductive material includes a carbon-based material and a metal fluoride disposed on a surface of the carbon-based material.