Multilayer Positive Electrode for Battery Resistivity and Packing

Solution Overview

Problem

The mixing of single-particles with aggregated particles in positive electrode active material layers of nonaqueous electrolyte secondary batteries increases resistivity, compromising both packing characteristics and energy density.

Innovation Solution

A multilayer structure is implemented in the positive electrode active material layer, with a first layer composed mainly of aggregated particles to reduce resistivity and a second layer containing a mixture of aggregated and single-particles to enhance packing characteristics, using a specific thickness ratio to balance both factors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If single-particles are mixed with aggregated particles to improve packing characteristic, then energy density is improved, but resistivity increases and input/output characteristic decreases

Engineering Contradiction:

Improvepacking characteristicVSAvoidresistivity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The positive electrode active material layer is divided into two distinct layers: a first layer containing aggregated particles and a second layer containing single-particles. This segmentation allows each layer to fulfill its specific function - the first layer maintains low resistivity while the second layer improves packing characteristic, thereby resolving the contradiction between energy density and resistivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode active material layer are assigned different compositions and properties. The first layer (near the positive electrode substrate) has low resistivity to ensure good electrical contact, while the second layer (farther from substrate) has high packing density to maximize energy density. This local differentiation resolves the contradiction by optimizing each region for its specific purpose

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If single-particles are used to enhance packing characteristic, then energy density is improved, but manufacturing complexity increases due to multilayer structure

Engineering Contradiction:

Improvepacking characteristicVSAvoidstructure complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The positive electrode active material layer is divided into two distinct layers: a first layer containing aggregated particles and a second layer containing single-particles. This segmentation allows each layer to fulfill its specific function - the first layer maintains low resistivity while the second layer improves packing characteristic, thereby resolving the contradiction between energy density and resistivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the positive electrode active material layer are assigned different compositions and properties. The first layer (near the positive electrode substrate) has low resistivity to ensure good electrical contact, while the second layer (farther from substrate) has high packing density to maximize energy density. This local differentiation resolves the contradiction by optimizing each region for its specific purpose

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS20220302444A1Positive electrode and nonaqueous electrolyte secondary battery

Publication Date: 2022.09.22 PRIME PLANET ENERGY & SOLUTIONS INC

AI summary

A positive electrode is used for a nonaqueous electrolyte secondary battery. The positive electrode includes a positive electrode substrate and a positive electrode active material layer. The positive electrode active material layer is disposed on a surface of the positive electrode substrate. The positive electrode active material layer includes a first layer and a second layer. The second layer is disposed between the positive electrode substrate and the first layer. The first layer includes a first positive electrode active material. The first positive electrode active material includes first aggregated particles. The second layer includes a second positive electrode active material. The second positive electrode active material includes second aggregated particles and single-particles. Each of the first aggregated particles and the second aggregated particles is formed by aggregation of 50 or more primary particles. The single-particles have an arithmetic mean diameter larger than the primary particles.