Composite Cathode Coating to Suppress Battery Interface Resistance

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Solution Overview

Problem

Existing battery technologies face issues with increased output resistance due to oxidative decomposition of halide solid electrolytes and thermal stability, leading to decreased charge-discharge efficiency and increased internal resistance.

Innovation Solution

A composite positive electrode active material is developed, featuring a fluoride solid electrolyte coating layer that reacts with water and hydrogen fluoride to inhibit the formation of resistive layers, comprising a first coating material with lithium, titanium, and a second material that forms lithium oxide and lithium fluoride, thereby improving ionic conductivity and preventing resistive layer formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a halide solid electrolyte is used as a coating layer, then the initial ionic conductivity is improved, but the output resistance increases due to oxidative decomposition when heat is applied

Engineering Contradiction:

Improveionic conductivityVSAvoidthermal stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies composite materials by combining fluoride solid electrolyte and oxide materials in a coating layer. This composite structure maintains high ionic conductivity while the oxide component prevents oxidative decomposition of the halide solid electrolyte under thermal conditions, thereby resolving the contradiction between initial ionic conductivity and thermal stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The fluoride solid electrolyte acts as an intermediary layer between the positive electrode active material and the halide solid electrolyte. This intermediary coating prevents direct contact and oxidative decomposition between the halide electrolyte and the electrode material during thermal conditions, maintaining both ionic conductivity and thermal stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If the positive electrode active material is coated with a single material, then the manufacturing process is simple, but the charge-discharge efficiency decreases due to resistive layer formation

Engineering Contradiction:

Improvecoating process simplicityVSAvoidcharge-discharge efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent uses a composite coating layer containing fluoride solid electrolyte and oxide materials. This composite structure prevents resistive layer formation during charge-discharge cycles while maintaining a relatively simple coating process, thus resolving the contradiction between manufacturing simplicity and charge-discharge efficiency.

Inventive Principle:

Principle #40Composite materials

3Stability of the object's composition

If a fluoride solid electrolyte coating is applied, then thermal stability is improved, but the output resistance increases due to reaction with water and hydrogen fluoride

Engineering Contradiction:

Improvethermal stabilityVSAvoidoutput resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The oxide material in the composite coating acts as an intermediary that reacts with water and hydrogen fluoride to form stable compounds. This protects the fluoride solid electrolyte from harmful reactions while maintaining thermal stability and preventing output resistance increase.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potentially harmful reaction between oxide and water/hydrogen fluoride into a beneficial effect. The oxide material sacrificially reacts with these substances to form stable compounds, protecting the fluoride solid electrolyte and actually improving overall battery performance and stability.

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 solution effectively inhibits the increase in output resistance associated with heat application, enhancing the battery's thermal stability and charge-discharge efficiency by preventing the formation of resistive layers at the electrode-electrolyte interface.

Implementation Method 1

The second coating material is a material that reacts with at least one selected from the group consisting of water and hydrogen fluoride, to form at least one selected from the group consisting of lithium oxide and lithium fluoride

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Implementation Method 2

the coating layer contains a first coating material and a second coating material... The second coating material is a material that reacts with at least one selected from the group consisting of water and hydrogen fluoride

Methodology Applied

Scientific EffectChemical reaction: Chemical Bonding

Data Source

PatentUS20240055598A1Composite positive electrode active material, positive electrode material, and battery

Publication Date: 2024.02.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A composite positive electrode active material includes a positive electrode active material and a coating layer coating at least a portion of a surface of the positive electrode active material. The coating layer contains a first coating material and a second coating material. The first coating material is a fluoride solid electrolyte, and the second coating material is a material that reacts with at least one selected from the group consisting of water and hydrogen fluoride, to form at least one selected from the group consisting of lithium oxide and lithium fluoride.