Positive Electrode Material with Metal Gradients for Li-Ion Diffusion

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Solution Overview

Problem

High-Ni lithium composite oxides used in lithium secondary batteries face issues with increased resistance and structural instability, leading to deteriorated lifetime and irreversible capacity loss due to insufficient lithium ion and charge diffusion, particularly on the surface of the battery.

Innovation Solution

A positive electrode active material is developed with primary particles that have regions of different transition metal concentrations, such as Ni, Co, and Mn, which are locally formed to enhance lithium ion and charge diffusion, and a coating layer is applied to improve structural stability and electrochemical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If high-Ni lithium composite oxide is used to increase energy density, then capacity is improved, but resistance increases and lifetime deteriorates

Engineering Contradiction:

Improveenergy densityVSAvoidlifetime

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by creating a concentration gradient of transition metals within the lithium composite oxide particles. The core region has a different composition (lower Ni content) compared to the surface region (higher Ni content), allowing the surface to provide high capacity while the core maintains structural stability and low resistance, thus resolving the contradiction between energy density and lifetime.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses composite materials by combining multiple transition metals (Ni, Co, Mn) in a gradient distribution within the lithium composite oxide structure. This composite approach allows different regions to contribute different properties: the high-Ni surface provides high capacity while the low-Ni core provides stability, achieving both high energy density and long lifetime.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Ni content is increased to improve reversible capacity, then capacity is improved, but structural stability decreases

Engineering Contradiction:

Improvereversible capacityVSAvoidstructural stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent implements local quality by spatially varying the Ni concentration within the particles. The surface region has high Ni content to maximize reversible capacity, while the core region has lower Ni content to maintain structural stability during charge-discharge cycles, thus resolving the contradiction between capacity and structural stability.

Inventive Principle:

Principle #3Local quality

3Power

If Ni content is increased to improve output characteristics, then power is improved, but resistance increases

Engineering Contradiction:

Improveoutput characteristicsVSAvoidresistance

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a core-shell gradient structure where the surface region has high Ni content to provide excellent output characteristics and power, while the core region has lower Ni content to maintain low resistance. This spatial differentiation allows the material to simultaneously achieve high power output and low resistance.

Inventive Principle:

Principle #3Local quality

4Ease of manufacture

If uniform transition metal concentration is used, then manufacturing is simple, but lithium ion diffusion is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidlithium ion diffusion

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent implements local quality by creating a controlled concentration gradient of transition metals from core to surface. This gradient structure facilitates lithium ion diffusion by providing compositional pathways that optimize ion transport, while the gradient can be achieved through controlled synthesis methods that balance manufacturing complexity with performance improvement.

Inventive Principle:

Principle #3Local quality

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 improves lithium ion and charge diffusion efficiency, reduces resistance, and enhances the structural stability of the battery, leading to improved capacity retention and lifespan of lithium secondary batteries.

Implementation Method 1

a lithium secondary battery storing electrical energy by means of a difference in chemical potential when lithium ions are intercalated/deintercalated into/from a positive electrode and a negative electrode

Methodology Applied

Scientific EffectIntercalation: Absorption (physical)

Implementation Method 2

increased efficiency in diffusion of lithium ions and/or charges

Methodology Applied

Scientific EffectDiffusion: Diffusion

Data Source

PatentUS20230411605A1Positive electrode active material and lithium secondary battery comprising the same

Publication Date: 2023.12.21 ECOPRO BM CO LTD

AI summary

The present invention relates to a positive electrode active material, and a lithium secondary battery using a positive electrode including the same. More particularly, the present invention relates to a positive electrode active material that has increased efficiency in the diffusion of lithium ions and/or charges and increased structural stability by locally forming regions with different concentrations of an arbitrary transition metal in a primary particle, and a lithium secondary battery using a positive electrode including the same.