Radial Nickel-Based Cathode Material for Lithium Battery

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Solution Overview

Problem

Rechargeable lithium batteries using lithium nickel manganese cobalt composite oxides face issues with cycle-life reduction, increased resistance, and insufficient capacity due to cracks in the positive active material during charging and discharging.

Innovation Solution

A positive active material for rechargeable lithium batteries is developed, comprising a first nickel-based material with a secondary particle structure of agglomerated primary particles having a radial arrangement and a second nickel-based material with a monolith structure, both subjected to specific heat-treatments in an oxidizing gas atmosphere to enhance stability and electrochemical characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium nickel manganese cobalt composite oxide is used as positive active material, then capacity characteristics are improved, but cycle-life is decreased due to cracks generated during charging and discharging

Engineering Contradiction:

ImprovecapacityVSAvoidcycle-life

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The positive active material is divided into primary particles and secondary particles, where primary particles are aggregated to form secondary particles with controlled morphology. This segmentation allows the material to maintain structural integrity while accommodating volume changes during lithium insertion/extraction, reducing crack formation and improving cycle-life while preserving capacity.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If lithium nickel manganese cobalt composite oxide is used as positive active material, then capacity characteristics are improved, but resistance is increased due to cracks generated during charging and discharging

Engineering Contradiction:

ImprovecapacityVSAvoidresistance

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The secondary particle structure with controlled primary particle aggregation provides a buffer zone that accommodates volume expansion and contraction during charging and discharging cycles. This pre-designed structural flexibility prevents crack formation that would otherwise increase resistance, thereby maintaining low resistance while preserving high capacity characteristics.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If residual lithium is present in positive active material, then manufacturing is simplified, but stability is decreased

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent controls the residual lithium content within a specific range (0.01-0.05 mol ratio) rather than completely eliminating it. This parameter optimization maintains structural stability and prevents degradation while avoiding excessive complex manufacturing processes, achieving a balance between stability and manufacturing simplicity.

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 solution results in improved lithium diffusivity, reduced crack generation, and enhanced cycle-life characteristics, along with decreased residual lithium and increased electrode plate density, leading to a rechargeable lithium battery with improved stability and electrochemical performance.

Implementation Method 1

subjecting a first precursor to a first heat-treatment in an oxidizing gas atmosphere to obtain a first nickel-based oxide, subjecting a second precursor to a second heat-treatment in an oxidizing gas atmosphere to obtain a second nickel-based oxide

Methodology Applied

Scientific EffectHeat-treatment: Heat Treatment

Implementation Method 2

subjecting a first precursor to a first heat-treatment in an oxidizing gas atmosphere to obtain a first nickel-based oxide

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

improved lithium diffusivity

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS11682755B2Positive active material for rechargeable lithium battery, preparing method thereof and rechargeable lithium battery comprising positive electrode including positive active material

Publication Date: 2023.06.20 SAMSUNG SDI CO LTD

AI summary

A positive active material for a rechargeable lithium battery includes a first positive active material including a secondary particle including at least two agglomerated primary particles, where at least one part of the primary particles has a radial arrangement structure, as well as a second positive active material having a monolith structure. The first and second positive active materials may both include nickel-based positive active materials. A method of preparing the positive active material, and a rechargeable lithium battery including a positive electrode including the positive active material are also provided.