High-Ni Cathode Material with Bimodal Particles for Structural Stability

Solution Overview

Problem

High-Ni positive electrode active materials in lithium secondary batteries suffer from structural instability, leading to degradation at both high and room temperatures, due to cation mixing and the generation of lithium by-products like LiOH and Li2CO3, which affect battery performance and lifespan.

Innovation Solution

A bimodal-type positive electrode active material with a high Ni content, comprising a combination of small and large lithium composite oxide particles, optimized with a specific composition and structure to enhance electrochemical properties and stability, including a coating layer to reduce residual lithium and improve crystal structure integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-Ni positive electrode active material is used to increase capacity, then battery capacity is improved, but structural stability deteriorates due to Li/Ni cation mixing

Engineering Contradiction:

Improvebattery capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the core. The surface is enriched with Ni while the core maintains Li-rich composition, allowing the surface to provide high capacity while the core provides structural stability and prevents cation mixing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining multiple phases with different compositions - a Li-rich core phase and a Ni-rich surface phase. This composite structure allows the material to simultaneously exhibit high capacity (from Ni-rich surface) and high stability (from Li-rich core), resolving the contradiction between capacity and structural stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If high-Ni positive electrode active material is used to increase capacity, then battery capacity is improved, but thermal stability deteriorates

Engineering Contradiction:

Improvebattery capacityVSAvoidthermal stability

Core Design Contradiction:

Quantity of substanceVSTemperature

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the core. The surface is enriched with Ni while the core maintains Li-rich composition, allowing the surface to provide high capacity while the core provides structural stability and prevents cation mixing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining multiple phases with different compositions - a Li-rich core phase and a Ni-rich surface phase. This composite structure allows the material to simultaneously exhibit high capacity (from Ni-rich surface) and high stability (from Li-rich core), resolving the contradiction between capacity and structural stability.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If high-Ni positive electrode active material is used to increase capacity, then battery capacity is improved, but battery lifespan deteriorates due to Li by-products generation

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifespan

Core Design Contradiction:

Quantity of substanceVSDuration of action of moving object

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the surface region has different composition and properties from the core. The surface is enriched with Ni while the core maintains Li-rich composition, allowing the surface to provide high capacity while the core provides structural stability and prevents cation mixing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining multiple phases with different compositions - a Li-rich core phase and a Ni-rich surface phase. This composite structure allows the material to simultaneously exhibit high capacity (from Ni-rich surface) and high stability (from Li-rich core), resolving the contradiction between capacity and structural stability.

Inventive Principle:

Principle #40Composite materials

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 maintains high capacity characteristics while improving structural stability and thermal stability, reducing side reactions with the electrolyte and enhancing the battery's lifespan and energy density.

Implementation Method 1

when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode

Methodology Applied

Scientific EffectIntercalation:

Implementation Method 2

including a coating layer to reduce residual lithium and improve crystal structure integrity

Methodology Applied

Scientific EffectSurface coating: Coatings

Data Source

PatentUS11811060B2Positive electrode active material and lithium secondary battery comprising the same

Publication Date: 2023.11.07 ECOPRO BM CO LTD

AI summary

The present invention relates to a positive electrode active material and a lithium secondary battery including the same, and more particularly, to a positive electrode active material which exhibits a predetermined peak intensity ratio and a predetermined voltage ratio in a graph illustrating the voltage (V) and the battery capacity (Q) at the 3rd cycle and having an X axis indicating the voltage (V) and a Y axis indicating a value (dQ/dV) obtained by differentiating the battery capacity (Q) with respect to the voltage (V) when charging/discharging is performed under predetermined conditions, and a lithium secondary battery including the same.