Boron Coated Positive Electrode for Sulfide Solid-State Batteries

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Solution Overview

Problem

Sulfide-based solid electrolytes in all-solid-state batteries react with positive electrode active materials at the interface, leading to deteriorated electrochemical performance and unsatisfactory charge/discharge characteristics.

Innovation Solution

A method involving thermal treatment of dried positive electrode active material particles with boron to form a boron-based coating layer, which inhibits interface reactions and improves the surface properties of the particles, enhancing charge/discharge characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a sulfide-based solid electrolyte is used to achieve high ion conductivity, then the ion conductivity is improved, but the electrolyte reacts with the positive electrode active material at the interface, forming a resistive new phase that deteriorates electrochemical performance

Engineering Contradiction:

Improveion conductivityVSAvoidelectrochemical performance

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A boron-based coating layer is introduced as an intermediary substance between the sulfide-based solid electrolyte and the positive electrode active material. This coating layer prevents direct contact and reaction between the electrolyte and active material, eliminating the formation of resistive new phases while maintaining high ion conductivity through the sulfide-based electrolyte.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The boron-based coating layer is applied in advance to the positive electrode active material surface before assembling the battery. This preliminary protective action prevents the harmful reaction between the sulfide-based solid electrolyte and the active material from occurring, thereby preserving electrochemical performance throughout the battery's operational life.

Inventive Principle:

Principle #9Preliminary anti-action

2Reliability

If a wet-type coating process is used to form a reaction barrier layer, then the surface passivation is achieved, but the manufacturing process becomes complex and produces significant byproducts

Engineering Contradiction:

Improvesurface passivationVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The wet-type coating process (which involves liquid precursors, drying, and complex thermal treatment) is replaced with a dry-type coating method using boron powder. This substitution simplifies the manufacturing process by eliminating the need for solvent evaporation and complex drying steps, while still achieving effective surface passivation through the boron-based coating layer.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

Boron powder, a simple and inexpensive material, is used as the coating source instead of complex precursor solutions. The boron powder is directly applied and thermally treated to form the protective coating, eliminating the need for expensive precursors and reducing manufacturing waste and byproducts.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 method results in improved charge/discharge characteristics and increased capacity of sulfide-based all-solid-state batteries, with a simplified manufacturing process and reduced byproducts, compared to conventional wet-type processes.

Implementation Method 1

a method of improving the positive electrode active material, particularly a coating method that is capable of passivating the surface of the positive electrode active material, has been proposed. Passivation is a process of treating the surface of a material such that the inherent properties thereof are prevented from being changed by external conditions or stimulation.

Methodology Applied

Scientific EffectPassivation:

Implementation Method 2

mixing and thermally treating the positive electrode active material particle and boron

Methodology Applied

Scientific EffectThermal treatment: Heat Treatment

Data Source

PatentUS11575116B2Positive electrode active material particle for sulfide-based all-solid-state batteries

Publication Date: 2023.02.07 LG ENERGY SOLUTION LTD

AI summary

A method of treating the surface of a positive electrode active material that is capable of inhibiting a reaction at the interface between a sulfide-based solid electrolyte and the positive electrode active material. A positive electrode active material particle for sulfide-based all-solid-state batteries, the surface of which is reformed, using the method and a sulfide-based all-solid-state battery, the charge/discharge characteristics of which are improved, including the same are also disclosed. The positive electrode active material particle for sulfide-based all-solid-state batteries manufactured using a dry-type method exhibits larger capacity than a positive electrode active material particle for sulfide-based all-solid-state batteries manufactured through a conventional wet-type process. In addition, the manufacturing process is simplified, and the amount of byproducts is reduced.