Positive Electrode Active Material Powder for High-Density Rolling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium ion battery positive electrodes face challenges in achieving high density while preventing substrate elongation and brittleness during rolling, leading to potential breakage and reduced cycle durability due to inadequate packing characteristics of the active material powder.

Innovation Solution

A positive electrode active material powder comprising a combination of large single-particles and aggregated particles, with a flow function coefficient of 2.9 or higher, is used to enhance packing characteristics during rolling, reducing substrate elongation and improving energy density and cycle durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If pressing force during rolling is increased to increase the density of the positive electrode active material layer, then the density is improved, but the elongation of the positive electrode substrate becomes large, making it brittle and prone to breakage

Engineering Contradiction:

Improvedensity of positive electrode active material layerVSAvoidstrength of positive electrode substrate

Core Design Contradiction:

Volume of stationary objectVSStrength

Solution Approach 1:

The invention changes the particle size distribution parameters of the active material powder, specifically controlling the ratio of fine particles (D10) to coarse particles (D90) to be 0.03 or more. This parameter change improves packing characteristics, allowing high density to be achieved with reduced rolling pressure, thereby preventing substrate elongation and breakage

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention uses a composite particle size distribution consisting of multiple particle size ranges (fine particles with D10 ≥ 0.03 μm, intermediate particles, and coarse particles with D90 ≤ 10 μm). This composite structure optimizes packing efficiency and reduces the pressing force required during rolling, resolving the contradiction between density and substrate strength

Inventive Principle:

Principle #40Composite materials

2Volume of stationary object

If the positive electrode active material powder has poor packing characteristics, then the density of the positive electrode active material layer is low, but increasing pressing force to compensate causes excessive elongation of the positive electrode substrate

Engineering Contradiction:

Improvedensity of positive electrode active material layerVSAvoidease of rolling process

Core Design Contradiction:

Volume of stationary objectVSEase of operation

Solution Approach 1:

The invention optimizes the particle size distribution parameters, specifically setting the ratio of fine particles (D10) to coarse particles (D90) at 0.03 or more. This parameter optimization improves packing characteristics, enabling high density to be achieved without excessive pressing force, thus facilitating easier rolling operations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention introduces fine particles (with D10 ≥ 0.03 μm) into specific regions of the particle size distribution to fill voids between larger particles. This local quality enhancement improves overall packing efficiency without requiring increased pressing force, making the rolling process easier to control

Inventive Principle:

Principle #3Local quality

3Reliability

If the positive electrode substrate is elongated during rolling, then the positive electrode may be broken during roll-to-roll transfer, but reducing pressing force decreases the density of the active material layer

Engineering Contradiction:

Improvereliability of positive electrode during transferVSAvoiddensity of positive electrode active material layer

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The invention changes the particle size distribution parameters, specifically controlling the ratio of fine particles (D10) to coarse particles (D90) to be 0.03 or more. This parameter change improves packing characteristics, allowing high density to be achieved with reduced pressing force, thereby preventing substrate elongation and breakage during transfer

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention performs preliminary optimization of particle size distribution before the rolling process. By pre-configuring the powder with optimal packing characteristics (D10/D90 ≥ 0.03), the need for high pressing force is eliminated beforehand, preventing substrate damage during subsequent transfer operations

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12148918B2Positive electrode active material powder, positive electrode, lithium ion battery, and method of producing positive electrode

Publication Date: 2024.11.19 PRIME PLANET ENERGY & SOLUTIONS INC

AI summary

A positive electrode active material powder includes a first particle group and a second particle group. The first particle group consists of a plurality of first particles. Each of the first particles includes 1 to 10 single-particles. The second particle group consists of a plurality of second particles. Each of the second particles includes an aggregated particle. The aggregated particle is formed by aggregation of 50 or more primary particles. The positive electrode active material powder has a flow function coefficient of more than or equal to 2.9. The flow function coefficient is a ratio of a maximum principal stress to a uniaxial collapse stress. The uniaxial collapse stress and the maximum principal stress are measured by a direct shear test for powders.