Core-Shell Positive Electrode Active Material for Lithium Ion Battery

Solution Overview

Problem

Lithium nickel composite oxide with high nickel abundance ratio exhibits poorer lifetime characteristics, limiting its practical use in lithium ion secondary batteries, necessitating improved energy density and extended cycle life.

Innovation Solution

A positive electrode active material comprising a mixture of nickel composite oxide particles with a lamellar crystal structure, where the ratio of Ni exceeds 90%, and additional particles with different substitution elements and ratios, are used to balance charge and discharge reactions, reducing particle cracking and uneven intralayer reactions, thereby enhancing energy density and lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium nickel composite oxide with high nickel abundance ratio is used, then energy density is improved, but lifetime characteristics deteriorate

Engineering Contradiction:

Improveenergy densityVSAvoidlifetime characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the inner core region contains nickel composite oxide with high nickel abundance ratio (0.90 ≤ x < 1.0) for high energy density, while the outer shell region contains nickel composite oxide with lower nickel abundance ratio (0.80 ≤ x < 0.90) for improved stability and lifetime characteristics. This spatial differentiation of material composition allows simultaneous optimization of both energy density and lifetime performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining two different nickel composite oxide compositions with distinct nickel abundance ratios to form a multi-region positive electrode active material. The composite structure integrates the high-capacity characteristics of high-nickel material with the high-stability characteristics of low-nickel material, achieving synergistic improvement in both energy density and lifetime characteristics.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If high nickel abundance ratio is used, then capacity is increased, but particle cracking occurs

Engineering Contradiction:

ImprovecapacityVSAvoidparticle integrity

Core Design Contradiction:

Quantity of substanceVSStrength

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the inner core region contains nickel composite oxide with high nickel abundance ratio (0.90 ≤ x < 1.0) for high energy density, while the outer shell region contains nickel composite oxide with lower nickel abundance ratio (0.80 ≤ x < 0.90) for improved stability and lifetime characteristics. This spatial differentiation of material composition allows simultaneous optimization of both energy density and lifetime performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs beforehand cushioning by forming an outer shell of lower-nickel material that acts as a protective layer before the high-nickel core undergoes volume expansion and contraction during charge-discharge cycles. This outer shell cushions the mechanical stress and prevents particle cracking from propagating into the high-capacity core region.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Use of energy by moving object

If high nickel abundance ratio is used, then energy density is improved, but uneven intralayer reactions occur

Engineering Contradiction:

Improveenergy densityVSAvoidreaction uniformity

Core Design Contradiction:

Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by creating a core-shell structure where the inner core region contains nickel composite oxide with high nickel abundance ratio (0.90 ≤ x < 1.0) for high energy density, while the outer shell region contains nickel composite oxide with lower nickel abundance ratio (0.80 ≤ x < 0.90) for improved stability and lifetime characteristics. This spatial differentiation of material composition allows simultaneous optimization of both energy density and lifetime performance.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs parameter changes by varying the nickel abundance ratio parameter across different spatial regions of the positive electrode active material. The nickel content transitions from lower values (0.80-0.89) in the outer shell to higher values (0.90-0.99) in the inner core, creating a gradient structure that optimizes both reaction uniformity and energy density.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3573155B1Positive electrode active substance, positive electrode, and lithium ion secondary cell

Publication Date: 2023.07.05 ENVISION AESC JAPAN LTD

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AI summary

A positive electrode active material according to the present invention is a positive electrode active material that is used in a positive electrode for a lithium ion secondary battery. This positive electrode active material includes positive electrode active material particles A represented by Formula (A) : LiαNixCoyM1(1-x-y)O2 (where 0<α≤1.15, 0.90<x≤0.98, 0<y≤0.10, and 0<(1-x-y)), and positive electrode active material particles B represented by Formula (B): LiβNiaCobM2(1-a-b)O2 (where 0<β≤1.15, 0.70≤a≤0.90, 0<b≤0.20, and 0<(1-a-b)). M1 and M2 each independently represent one element or two or more elements selected from the group consisting of Li, B, Mg, Al, Fe, and Mn.