Cathode Coating Composition for Stable Solid-State Lithium Batteries

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Solution Overview

Problem

Existing positive electrode active materials for rechargeable lithium batteries suffer from structural instability and low ionic conductivity, leading to deteriorated cycle-life and capacity characteristics, particularly in all-solid-state batteries, and there is a need for materials that improve interfacial stability with solid electrolytes.

Innovation Solution

A positive electrode active material with a coating layer containing ZrO2 and Li6Zr2O7 is applied to lithium transition metal composite oxide particles, enhancing structural stability and ionic conductivity through a dry coating method, which forms a uniform and thin coating layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating layer is applied to improve structural stability and ionic conductivity, then capacity and cycle-life characteristics are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecycle-life characteristicsVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The coating layer materials (ZrO2 and Li6Zr2O7) are pre-mixed with the lithium transition metal composite oxide particles before sintering. This preliminary mixing ensures uniform distribution of coating materials throughout the electrode material, eliminating the need for subsequent coating steps and simplifying the manufacturing process while ensuring consistent protective coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The coating layer formation is merged with the sintering process. By adding coating materials to the raw mixture before sintering, the coating formation occurs simultaneously with the main material synthesis, combining two processes into one and reducing manufacturing complexity while achieving both structural stability and ionic conductivity improvements.

Inventive Principle:

Principle #5Merging (Combining)

2Stability of the object's composition

If a coating layer is applied to suppress reaction with solid electrolyte, then interfacial stability is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveinterfacial stabilityVSAvoidcoating uniformity control

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The coating materials are pre-distributed throughout the electrode material matrix before sintering. This preliminary distribution ensures that coating materials are uniformly present at all particle surfaces and interfaces, eliminating the need for precise post-sintering coating applications and reducing manufacturing precision requirements while achieving consistent interfacial stability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The electrode material is created as a composite containing both the lithium transition metal composite oxide and the coating materials (ZrO2 and Li6Zr2O7) in a unified structure. This composite approach ensures that protective coating materials are inherently integrated throughout the material, providing uniform interfacial stability without requiring separate coating steps with high precision control.

Inventive Principle:

Principle #40Composite materials

3Productivity

If a dry coating method is used to enable mass production, then productivity is improved, but coating uniformity control becomes more difficult

Engineering Contradiction:

Improvemass production capabilityVSAvoidcoating thickness control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The coating material application is merged with the bulk material mixing process. By incorporating coating materials into the raw material mixture before sintering, the coating application occurs during the standard mixing and sintering operations, enabling mass production without requiring separate coating equipment or processes, while the sintering process itself ensures uniform distribution and thickness control.

Inventive Principle:

Principle #5Merging (Combining)

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 layer improves the capacity and cycle-life characteristics of rechargeable lithium batteries by reducing reactivity with solid electrolytes and interfacial resistance, facilitating lithium ion movement, and enabling mass production.

Implementation Method 1

suppressing the reaction between the positive electrode active material and the solid electrolyte

Methodology Applied

Scientific EffectChemical inertness:

Implementation Method 2

increasing ionic conductivity

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Implementation Method 3

heat treating the mixture at 420 °C to 580 °C

Methodology Applied

Scientific EffectThermal decomposition: Pyrolysis

Data Source

PatentEP4685868A1Positive active material for rechargeable lithium batteries, method for preparing same, and positive electrode for rechargeable lithium batteries, rechargeable lithium battery, and all-solid-state rechargeable battery, comprising same

Publication Date: 2026.01.28 SAMSUNG SDI CO LTD

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AI summary

Disclosed are a positive electrode active material for a rechargeable lithium battery including particles containing a lithium transition metal composite oxide, and a coating layer located on the surface of the particles and containing ZrO2 and Li6Zr2O7, a preparation method thereof, and a positive electrode, rechargeable lithium battery, and an all-solid-state rechargeable battery.