Solid-State Battery Sulfur Electrode Complex Hydride Interface

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Solution Overview

Problem

Current solid-state lithium ion batteries face challenges with low ion conductivity, stability issues, and increased resistance due to reactions between solid electrolytes and electrode materials, particularly with complex hydrides and sulfur-based active materials, which affect long-term battery performance and safety.

Innovation Solution

A solid-state battery configuration using a sulfur-based electrode active material doped with lithium, combined with a complex hydride solid electrolyte like LiBH4, and an alkali metal compound, which forms a stable interface and maintains high ion conductivity, reducing interfacial resistance and enhancing long-term stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If sulfides are used as solid electrolyte to achieve high lithium ion conductivity, then ion conductivity is improved, but reaction with negative electrode material occurs causing stability deterioration

Engineering Contradiction:
Improvelithium ion conductivityVSAvoidstability of electrode active material
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces a coating layer as an intermediary between the sulfide solid electrolyte and the negative electrode active material. This coating layer prevents direct contact and reaction between the sulfide and electrode materials, thereby maintaining stability while preserving the high lithium ion conductivity of the sulfide electrolyte.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs composite material structures where the sulfide solid electrolyte is combined with coating materials to form a multi-layered composite. This composite approach allows the system to simultaneously achieve the high ion conductivity of sulfides and the chemical stability provided by the coating materials.

Inventive Principle:
Principle #40Composite materials

2Reliability

If oxides and phosphate compounds are used as solid electrolyte to improve stability, then reliability is improved, but interfacial resistance with electrode active material increases

Engineering Contradiction:
Improvestability of solid electrolyteVSAvoidinterfacial resistance
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses coating layers as intermediary substances between the oxide/phosphate solid electrolyte and the electrode active material. These coatings reduce the interfacial resistance that naturally forms at the interface, enabling better electrical contact while maintaining the stability benefits of oxide and phosphate electrolytes.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Manufacturing precision

If sintering at high temperature is applied to form solid electrolyte layer using oxides and phosphate compounds, then density is improved, but manufacturing time increases

Engineering Contradiction:
Improvedensity of solid electrolyte layerVSAvoidsintering time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent modifies the sintering parameters (temperature, time, atmosphere) to optimize the formation of the solid electrolyte layer. By carefully controlling these parameters, the patent achieves adequate density without requiring excessively long sintering times, thus balancing manufacturing precision with productivity.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If organic polymers are used as solid electrolyte to simplify manufacturing, then ease of manufacture is improved, but lithium ion conductivity at room temperature decreases

Engineering Contradiction:
Improveprocessability of solid electrolyteVSAvoidlithium ion conductivity
Core Design Contradiction:
Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent creates composite structures where organic polymer electrolytes are combined with other materials (such as inorganic fillers or coating layers) to enhance lithium ion conductivity while maintaining the manufacturing advantages of polymer-based electrolytes. This composite approach allows the system to overcome the low conductivity limitation of pure polymers.

Inventive Principle:
Principle #40Composite materials

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 configuration achieves high ion conductivity and excellent stability, enabling safe and convenient lithium doping and prolonged battery operation with maintained capacity and reduced resistance over charge/discharge cycles.

Implementation Method 1

a solid electrolyte layer disposed between the positive-electrode layer and the negative-electrode layer, wherein the solid electrolyte layer contains a complex hydride solid electrolyte

Methodology Applied
Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

a method for manufacturing a sulfur-based electrode active material doped with lithium

Methodology Applied
Scientific EffectDoping: Dopants

Implementation Method 3

oxides and phosphate compounds have low resistance to redox

Methodology Applied
Scientific EffectRedox reactions: Redox Reactions

Data Source

PatentEP3043412B1Solid-state battery and method for manufacturing electrode active material
Publication Date: 2020.04.29 MITSUBISHI GAS CHEM CO INC
  • EP3043412B1 patent drawingFigure 1~2
  • EP3043412B1 patent drawingFigure 3A~3B
  • EP3043412B1 patent drawingFigure 3C~3D

AI summary

One embodiment provides a solid-state battery that has a positive-electrode layer; a negative-electrode layer; and a lithium-ion-conducting solid electrolyte layer disposed between the positive-electrode layer and the negative-electrode layer. The positive-electrode layer contains a positive-electrode active material and a solid electrolyte comprising a hydride of a complex. Said positive-electrode active material is sulfur-based, and the solid electrolyte layer contains a solid electrolyte comprising a hydride of a complex.