Positive Electrode Coating for Stable Halide Solid-State Batteries

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Solution Overview

Problem

The formation of a high-resistance layer at the interface between the positive electrode material and the sulfide solid electrolyte in batteries leads to increased polarization and difficulty in operation, particularly when using a halide solid electrolyte, due to oxidation and decomposition of the electrolyte during charging.

Innovation Solution

A positive electrode material is developed with a coating material composed of LiaMbOcXd, where M is Ta or Nb, and X is Cl, Br, or I, which suppresses electron transfer and oxidation of the halide electrolyte, reducing resistance and enhancing lithium ion conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfide solid electrolyte is used in the battery, then high lithium ion conductivity is achieved, but an interface layer forms at the positive electrode interface after initial charging that increases battery resistance

Engineering Contradiction:

Improvelithium ion conductivityVSAvoidinterface layer formation increasing resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A coating layer comprising lithium fluoride (LiF) and lithium oxynitride (LiON) is applied to the positive electrode surface. This intermediary coating prevents direct contact between the positive electrode active material and the sulfide solid electrolyte, thereby preventing the formation of high-resistance interface layers while maintaining lithium ion conductivity. The coating acts as a protective mediator that eliminates harmful interfacial reactions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If a halide solid electrolyte is used during charging, then lithium ion transfer is facilitated, but oxidation and decomposition of the electrolyte occur leading to increased polarization and operational difficulty

Engineering Contradiction:

Improvelithium ion transfer efficiencyVSAvoidelectrolyte stability against oxidation

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The coating layer of lithium fluoride and lithium oxynitride serves as a protective intermediary between the positive electrode and the halide solid electrolyte. This coating prevents direct oxidation of the halide electrolyte by blocking electron transfer to the electrolyte, thereby maintaining electrolyte stability and preventing decomposition while still allowing efficient lithium ion transfer through the coating.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The coating transforms the potentially harmful oxidation reaction into a beneficial protective mechanism. By preventing direct contact between the positive electrode and halide electrolyte, the coating converts what would be a destructive oxidation process into a controlled interface that protects the electrolyte while maintaining functionality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 coating material effectively reduces battery resistance and improves charge and discharge efficiency by preventing electrolyte decomposition and maintaining effective reaction areas, allowing for high-potential stability and efficient lithium ion transfer.

Implementation Method 1

oxidation and decomposition of the electrolyte during charging

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

suppresses electron transfer and oxidation of the halide electrolyte

Methodology Applied

Scientific EffectElectron transfer:

Implementation Method 3

enhancing lithium ion conductivity

Methodology Applied

Scientific EffectLithium ion conductivity: Conduction (electrical)

Data Source

PatentUS12489142B2Positive electrode material and battery

Publication Date: 2025.12.02 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

The positive electrode material according to an aspect of the present disclosure includes a first solid electrolyte, a positive electrode active material, and a coating material coating the surface of the positive electrode active material. The first solid electrolyte is represented by the following compositional formula: LiaMbOcXd. In the compositional formula, a, b, c, and d are positive real numbers; M is at least one selected from the group consisting of Ta and Nb; and X is at least one selected from the group consisting of Cl, Br, and I.