NCM Cathode Coating Penetration for Rolling-Induced Particle Breakage

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Solution Overview

Problem

Lithium cobalt oxide (LiCoO2) limitations in battery applications due to cobalt price instability and supply issues, along with performance deterioration from particle breakage during electrode rolling in NCM-based lithium composite transition metal oxide batteries, which exposes uncoated portions and leads to side reactions with the electrolyte.

Innovation Solution

A method for producing a positive electrode material by forming a coating layer on the surface of NCM-based lithium composite transition metal oxide and post-treating it with moisture at 10-50% relative humidity followed by heat treatment to ensure the coating penetrates into the secondary particle, reducing side reactions and performance deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If surface coating is applied to NCM-based lithium composite transition metal oxide, then side reactions with electrolyte are reduced, but particle breakage during rolling exposes uncoated portions leading to performance deterioration

Engineering Contradiction:

Improvebattery performanceVSAvoidside reactions with electrolyte

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing surface coating before electrode rolling, and then conducting post-treatment after rolling to repair any damaged coating. This sequence ensures the coating is applied in advance and then restored if broken during the rolling process, preventing exposure of uncoated portions that would cause side reactions with electrolyte.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by applying a protective coating layer on the particle surface before the harmful rolling process. This coating acts as a cushion or protective barrier that prevents direct contact between the particle surface and electrolyte, reducing side reactions even when particles are subjected to mechanical stress during rolling.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Quantity of substance

If rolling is performed to improve electrode energy density, then energy density increases, but secondary particles break and uncoated portions are exposed

Engineering Contradiction:

Improveenergy densityVSAvoidcoating integrity

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements parameter changes by optimizing the rolling conditions (pressure, temperature, duration) and post-treatment parameters (heating temperature, atmosphere, time) to balance between achieving sufficient particle densification for energy density and maintaining coating integrity. By carefully controlling these parameters, the patent enables both high energy density and preserved coating quality.

Inventive Principle:

Principle #35Parameter changes

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 effectively covers primary particles inside the secondary particle, reducing side reactions and maintaining battery performance even during particle breakage, thus enhancing the energy density and capacity retention of lithium secondary batteries.

Implementation Method 1

a coating layer formed on the surface of a secondary particle of an NCM-based lithium composite transition metal oxide may penetrate into the inside of the secondary particle through post-treating

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

heat treating the lithium composite transition metal oxide to remove residual moisture

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 3

Lithium secondary batteries produce electric energy through an oxidation-reduction reaction occurring when lithium ions are intercalated/deintercalated into/from negative electrodes and positive electrodes

Methodology Applied

Scientific EffectOxidation-reduction reaction: Redox Reactions

Data Source

PatentUS12021228B2Method of producing positive electrode material for secondary battery

Publication Date: 2024.06.25 LG ENERGY SOLUTION LTD

AI summary

A method of producing a positive electrode material for a secondary battery includes preparing a lithium composite transition metal oxide containing nickel, cobalt, and manganese, forming a coating layer on a surface of the lithium composite transition metal oxide, and post-treating the lithium composite transition metal oxide having the coating layer formed thereon, wherein the post-treating is performed by exposing the lithium composite transition metal oxide having the coating layer formed thereon to moisture at a relative humidity of 10% to 50% at 25° C., and then heat treating the lithium composite transition metal oxide to remove residual moisture.