Fibrous Conductive Additive in All-Solid Cathode Layers

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Solution Overview

Problem

All-solid secondary batteries face a trade-off between conductivity and energy density due to the use of conductive additives, where increasing conductivity with more additives reduces the amount of cathode active material, thereby deteriorating energy density and cycle characteristics.

Innovation Solution

A cathode active material layer is developed with a sulfide solid electrolyte and a minimal amount of fibrous conductive additive, ranging from 0 to 0.4 wt%, which enhances conductivity without compromising energy density and cycle performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the amount of conductive additive in the cathode is increased to improve conductivity, then internal resistance decreases, but the amount of cathode active material decreases, resulting in deteriorated energy density

Engineering Contradiction:

ImproveconductivityVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the physical form parameter of the conductive additive from particle shape to fibrous shape, and optimizes its concentration parameter to 0.01-5 wt%, thereby achieving improved conductivity with minimal impact on energy density

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite cathode structure combining cathode active material particles with fibrous conductive additive, where the fibrous network provides conductivity pathways while the active material particles maintain energy storage capacity

Inventive Principle:

Principle #40Composite materials

2Reliability

If the amount of conductive additive is increased to improve conductivity, then internal resistance decreases, but cycle characteristics are deteriorated

Engineering Contradiction:

ImproveconductivityVSAvoidcycle characteristics

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent optimizes the concentration parameter of fibrous conductive additive to a specific range (0.01-5 wt%) and changes its morphological parameter to fibrous form, achieving a balance between conductivity improvement and cycle stability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the amount of cathode active material is decreased to accommodate more conductive additive, then conductivity improves, but energy density is deteriorated

Engineering Contradiction:

ImproveconductivityVSAvoidenergy density

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent develops a composite cathode where fibrous conductive additive and cathode active material coexist in an optimized ratio, creating a synergistic structure that provides both conductivity and energy storage without compromising either function

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS20210280873A1Cathode, all-solid secondary battery including cathode, and method of preparing all-solid secondary battery

Publication Date: 2021.09.09 SAMSUNG SDI CO LTD

AI summary

A cathode includes a cathode active material layer, wherein the cathode active material layer includes a cathode active material and a sulfide solid electrolyte, and wherein the cathode active material layer is free of a conductive additive or includes a fibrous conductive additive in a range of greater than 0 weight percent to about 0.4 weight percent, based on the total weight of the cathode active material layer.