Radial Nickel Cathode with Boron Coating for Battery Stability

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Solution Overview

Problem

Rechargeable lithium batteries using lithium nickel manganese cobalt composite oxides suffer from reduced cycle-life, increased resistance, and insufficient capacity due to structure collapse and side reactions caused by repeated charging and discharging.

Innovation Solution

A positive active material comprising a secondary particle with radially arranged primary particles and a monolith structure, where the surface of a nickel-based second positive active material is coated with a boron-containing compound, is developed to minimize structure collapse and side reactions, enhancing capacity retention and cycle-life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium nickel manganese cobalt composite oxide is used as positive active material, then high capacity is achieved, but cycle-life is decreased due to structure collapse and cracking during repeated 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 secondary particles are aggregates of multiple primary particles. This segmentation reduces internal stress and prevents cracking during charge-discharge cycles, improving cycle-life while maintaining high capacity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining lithium nickel manganese cobalt oxide with other materials to form a robust composite positive active material. This composite approach enhances structural stability and prevents degradation during repeated cycling, resolving the contradiction between high capacity and long cycle-life

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium nickel manganese cobalt composite oxide is used, then high capacity is achieved, but resistance is increased due to side reactions with electrolyte

Engineering Contradiction:

ImprovecapacityVSAvoidresistance

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

A coating layer is applied to the surface of the positive active material particles, serving as an intermediary barrier between the active material and the electrolyte. This coating reduces harmful side reactions that increase resistance, while allowing ionic transport to maintain high capacity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional positive active material structure is used, then manufacturing is simple, but structure collapse occurs during repeated charging and discharging

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidstructure stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention optimizes particle size parameters and structural characteristics of the positive active material. By controlling particle size distribution and morphology, the material achieves both structural stability during cycling and compatibility with existing manufacturing processes

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 a rechargeable lithium battery with improved high capacity, excellent capacity retention, and extended cycle-life by reducing structure collapse and side reactions, while maintaining high lithium diffusivity and conductivity.

Implementation Method 1

the surface of the second positive active material is coated with a boron-containing compound

Methodology Applied

Scientific EffectCoating: Coatings

Implementation Method 2

at least one part of the primary particles has a radial arrangement structure

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 3

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

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 4

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

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS11670754B2Positive active material for rechargeable lithium battery, preparing method thereof and rechargeable lithium battery comprising positive electrode including positive active material

Publication Date: 2023.06.06 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, wherein the first and second positive active materials may each include nickel-based positive active materials and the surface of the second positive active material is coated with a boron-containing compound. Further embodiments provide a method of preparing the positive active material, and a rechargeable lithium battery including a positive electrode including the positive active material.