Halide Coated Positive Electrode for All-Solid-State Battery

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Solution Overview

Problem

All-solid-state lithium batteries with sulfide solid electrolytes face increased resistance due to the formation of high-resistance layers at the interface between the positive electrode material and the sulfide solid electrolyte, leading to reduced battery performance.

Innovation Solution

A positive electrode material is developed with a coating material covering the surface of the active material, represented by the compositional formula LiaMbXc, where M includes calcium, yttrium, and a rare earth element, and X includes halogen elements like F, Cl, or Br, which inhibits electron transfer and prevents halogen oxidation, reducing battery resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sulfide solid electrolyte is used in an all-solid-state lithium battery, then high ion conductivity is achieved, but battery resistance increases due to the formation of a high-resistance interface layer between the positive electrode material and the sulfide solid electrolyte

Engineering Contradiction:

Improvebattery resistanceVSAvoidinterface layer formation

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A coating layer comprising a halide solid electrolyte (LiaMbXc where X is F, Cl, Br, or I) is applied to the surface of the positive electrode active material. This coating acts as an intermediary between the positive electrode active material and the sulfide solid electrolyte, preventing direct contact and the formation of high-resistance interface layers, thereby reducing battery resistance while maintaining high ion conductivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention uses a composite structure where a halide solid electrolyte coating is combined with the positive electrode active material. This composite approach leverages the properties of both materials: the halide coating provides resistance reduction and interface stability, while the positive electrode active material provides the necessary electrochemical activity, resulting in a battery with both low resistance and high performance.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the positive electrode active material directly contacts the sulfide solid electrolyte, then simple structure is maintained, but halogen oxidation occurs leading to increased resistance

Engineering Contradiction:

Improveresistance stabilityVSAvoidcoating structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The halide solid electrolyte coating serves as a protective intermediary layer that prevents direct contact between the positive electrode active material and the sulfide solid electrolyte. This coating specifically prevents halogen oxidation by blocking the interaction between the positive electrode material and the sulfide electrolyte, thereby stabilizing resistance without significantly complicating the overall battery structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enhances ion conductivity, leading to improved charge/discharge efficiency and energy density by preventing halogen oxidation and maintaining the integrity of the solid electrolyte.

Implementation Method 1

a coating material covering at least part of the surface of the positive electrode active material... which inhibits electron transfer and prevents halogen oxidation

Methodology Applied

Scientific EffectElectron transfer inhibition:

Implementation Method 2

a first solid electrolyte... represented by the compositional formula LiaMbXc... M includes calcium, yttrium, and at least one rare earth element other than yttrium

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS20230163299A1Positive electrode material and battery

Publication Date: 2023.05.25 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A positive electrode material includes a positive electrode active material, a first solid electrolyte, and a coating material covering at least part of the surface of the positive electrode active material. The first solid electrolyte is represented by the following compositional formula (1): LiaMbXc . . . Formula (1). In the compositional formula (1), a, b and c are each independently a positive real number, M includes calcium, yttrium, and at least one rare earth element other than yttrium, and X includes at least one selected from the group consisting of F, Cl, Br and I.