High-Nickel Electrode Sheet Edge Structure for Moisture Resistance

Solution Overview

Problem

Conventional high-nickel positive electrode active materials in lithium secondary batteries are prone to react with moisture, leading to reduced thermal stability and capacity, especially at the ends of the electrode sheet, limiting energy density and lifespan.

Innovation Solution

An electrode sheet design with a first positive electrode mixture layer in the central portion and a second positive electrode mixture layer at the edges, featuring a higher particle strength and potentially smaller particles, to minimize moisture reactivity while maintaining high energy density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the nickel content in the positive electrode active material is increased to improve energy density, then the energy density per volume increases, but the structural stability and chemical stability of the active material decrease, leading to rapid deterioration of thermal stability and increased reactivity with moisture

Engineering Contradiction:

Improveenergy densityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a dual-layer electrode structure where the edge regions contain a different positive electrode active material composition than the central portion. Specifically, the edge regions use a material with lower nickel content (8-15 mol% Ni) compared to the central portion (18-30 mol% Ni), allowing each region to have optimized properties for its specific function while maintaining overall high energy density

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining two different positive electrode active materials in a single electrode structure. The first material (for edges) has composition LiNi0.92Co0.04Mn0.04O2 and the second material (for center) has composition LiNi0.85Co0.07Mn0.08O2, creating a composite electrode that leverages the advantages of both materials to achieve both high energy density and improved stability

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the nickel content in the positive electrode active material is increased to improve energy density, then the capacity increases, but the reactivity with moisture increases, leading to increased gas generation during high temperature storage

Engineering Contradiction:

ImprovecapacityVSAvoidreactivity with moisture

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a dual-layer electrode structure where the edge regions contain a different positive electrode active material composition than the central portion. Specifically, the edge regions use a material with lower nickel content (8-15 mol% Ni) compared to the central portion (18-30 mol% Ni), allowing each region to have optimized properties for its specific function while maintaining overall high energy density

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful effect of high nickel reactivity with moisture into a benefit by strategically placing lower nickel content material at the edge regions where moisture penetration is highest. This transforms the potential weakness (lower nickel content) into a protective feature that prevents moisture-induced degradation while preserving the high capacity benefits of high nickel content in the central region

Inventive Principle:

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

3Duration of action of stationary object

If a second positive electrode active material with lower nickel content (20-40% Ni) is applied at both ends to suppress lithium precipitation, then the lifespan is improved, but the energy density cannot achieve the desired level

Engineering Contradiction:

ImprovelifespanVSAvoidenergy density

Core Design Contradiction:

Duration of action of stationary objectVSQuantity of substance

Solution Approach 1:

The patent applies local quality by creating a dual-layer electrode structure where the edge regions contain a different positive electrode active material composition than the central portion. Specifically, the edge regions use a material with lower nickel content (8-15 mol% Ni) compared to the central portion (18-30 mol% Ni), allowing each region to have optimized properties for its specific function while maintaining overall high energy density

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs parameter changes by precisely controlling the nickel content parameter in different regions of the electrode. The edge regions use material with 8-15 mol% Ni while the central portion uses 18-30 mol% Ni, representing a significant deviation from conventional uniform composition approaches. This parameter optimization enables simultaneous achievement of extended lifespan and high energy density

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12412886B2High-nickel electrode sheet having reduced reactivity with moisture and manufacturing method therefor

Publication Date: 2025.09.09 LG ENERGY SOLUTION LTD

AI summary

In the present invention, a slurry for a second cathode mixture is applied to both edge regions of an electrode sheet holing portion during storage of an electrode sheet having a high content of nickel, wherein the edge regions are vulnerable to moisture penetration and high in rolling reduction ratio and the slurry contains a cathode active material more resistant to rolling than that applied to the center region of the holding portion, whereby the reactivity of nickel and moisture is suppressed as much as possible to improve the lifespan characteristics of the battery.