Li2S Cathode Composite for Low-Resistance Solid-State Batteries

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Solution Overview

Problem

All solid secondary batteries face challenges with low ionic conductivity and high interfacial resistance due to the absence of solvents in their components, leading to reduced capacity and safety concerns.

Innovation Solution

A cathode is designed with a gamma sulfur-fibrous carbon-based material composite, incorporating Li2S as the cathode active material, which improves electronic and ionic conductivity, thereby enhancing specific capacity and capacity retention ratio.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high pressure is applied to improve ionic conductivity and uniform lithium deposition, then battery performance is enhanced, but device complexity and manufacturing difficulty increase

Engineering Contradiction:

Improveionic conductivityVSAvoidpressurization process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent creates locally optimized conductive pathways using carbon-coated active material particles and solid electrolyte positioned at interfaces. This local optimization of ionic and electronic conductivity networks enables good battery performance without requiring high external pressure, simplifying the manufacturing process.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The cathode structure is pre-designed with inherent conductivity pathways through the composite architecture of carbon-coated particles and solid electrolyte distribution. This preliminary structural optimization ensures good ionic and electronic conductivity from the start, eliminating the need for subsequent high-pressure treatment to achieve uniform lithium deposition and acceptable performance.

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 improved cathode structure enhances the specific capacity and capacity retention ratio of lithium secondary batteries, while also reducing the risk of fire or explosion by employing a solid electrolyte.

Implementation Method 1

the gamma sulfur-fibrous carbon-based material composite has a structure in which monoclinic gamma phase sulfur (S) is arranged on a fibrous carbon-based material

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a sulfide-based solid electrolyte, wherein the cathode active material includes Li2S, a Li2S composite, or a combination thereof

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS20250132333A1Cathode and lithium secondary battery including the same

Publication Date: 2025.04.24 SAMSUNG SDI CO LTD

AI summary

A lithium secondary battery including a cathode. The cathode includes a cathode current collector and a cathode active material layer on one or both sides of the cathode current collector and including a cathode active material, a gamma sulfur-fibrous carbon-based material composite, and a sulfide-based solid electrolyte, wherein the cathode active material includes Li2S, a Li2S composite, or a combination thereof, and the gamma sulfur-fibrous carbon-based material composite has a structure in which monoclinic gamma phase sulfur (S) is on a fibrous carbon-based material.