Lithium Battery Positive Electrode Active Material with Internal Voids

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Solution Overview

Problem

Lithium secondary battery positive electrode active materials face challenges in maintaining capacity retention, particularly in high temperature cycles, as existing materials do not effectively address porosity and void distribution within the particles.

Innovation Solution

A positive electrode active material comprising lithium composite metal oxide in the form of secondary particles with strategically located voids, where the voids are dispersed throughout the particles, enhancing contact area with the electrolyte and facilitating lithium ion desorption and insertion, characterized by specific void ratios and NMP liquid retention.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the porosity of the positive electrode active material is increased to improve capacity retention, then the capacity retention is improved, but the volumetric energy density deteriorates

Engineering Contradiction:

Improvecapacity retentionVSAvoidvolumetric energy density

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent applies porous materials by introducing voids within secondary particles of the positive electrode active material. These internal voids create pathways for electrolyte penetration and lithium ion transport, improving capacity retention while maintaining compact particle morphology for high volumetric energy density.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent employs nested doll principle by creating a hierarchical structure where primary particles aggregate to form secondary particles, which contain internal voids. This nested arrangement allows the material to maintain high density at the macro level while providing porous pathways at the micro level for improved ion transport and capacity retention.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If the porosity of the positive electrode active material is increased to improve capacity retention, then the capacity retention is improved, but the manufacturing precision deteriorates

Engineering Contradiction:

Improvecapacity retentionVSAvoidcontrol of void distribution

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by precisely controlling the void volume ratio within a specific range (5-40%) and regulating the size and distribution of voids. This parameter optimization allows the material to achieve improved capacity retention while maintaining manufacturability and consistent performance.

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 material exhibits excellent capacity retention in high temperature cycles and high volumetric energy density, with improved NMP liquid retention and discharge capacity, extending battery life.

Implementation Method 1

facilitating lithium ion desorption and insertion, characterized by specific void ratios and NMP liquid retention

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

NMP liquid retention of 18% or more, wherein the NMP liquid retention ratio is determined

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS11417879B2Positive electrode active material for lithium secondary batteries, positive electrode for lithium secondary batteries, and lithium secondary battery

Publication Date: 2022.08.16 TANAKA CHEM

AI summary

The present invention relates to a positive electrode active material for a lithium secondary battery, including a lithium composite metal oxide in a form of secondary particles formed by aggregation of primary particles, wherein the secondary particles have voids in interior thereof and a number of the voids with cross section thereof present per 1 μm2 of cross section of the secondary particles is 0.3 or more and 15 or less.