Doped Cathode Active Material for Stable Lithium Battery Crystal Structure

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Solution Overview

Problem

Lithium secondary batteries face issues with non-uniform chemical structures due to deformation of crystal structures in lithium-transition metal composite oxides, leading to capacity and lifespan deterioration.

Innovation Solution

A cathode active material for lithium secondary batteries is developed, featuring lithium-transition metal oxide particles with a Full Width at Half Maximum (FWHM) ratio of 400% or less, measured by in-situ X-ray Diffraction spectroscopy, and including at least two types of doping elements, which are uniformly distributed to enhance structural stability and prevent lattice and crystal structure distortion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium-transition metal composite oxide is used as cathode active material, then high operational voltage and energy density are achieved, but crystal structure deformation occurs leading to non-uniform chemical structure

Engineering Contradiction:

Improveenergy densityVSAvoidchemical structure uniformity

Core Design Contradiction:

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

Solution Approach 1:

The patent applies parameter changes by controlling the Full Width at Half Maximum (FWHM) of the (101) plane peak to be 0.250 or less, which directly addresses the crystal structure deformation issue. This parameter control ensures uniform chemical structure while maintaining the high energy density properties of lithium-transition metal composite oxide

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining lithium-transition metal oxide with specific doping elements (M1 and M2 from groups including Ti, Zr, Al, Mg, and W) in controlled ratios. This composite approach maintains structural uniformity while preserving the high energy density characteristics

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If lithium-transition metal composite oxide is used as cathode active material, then high capacity is achieved, but crystal structure deformation leads to shortened lifespan

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery lifespan

Core Design Contradiction:

Quantity of substanceVSDuration of action of stationary object

Solution Approach 1:

The patent controls the FWHM parameter of the (101) plane peak to be 0.250 or less, which prevents crystal structure deformation during charge-discharge cycles. This parameter control maintains both high capacity and extended lifespan by ensuring structural stability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies beforehand cushioning by pre-controlling the crystal structure uniformity through FWHM control and doping element addition before the battery operates. This preventive measure cushiones against future structure deformation that would otherwise reduce lifespan

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Stability of the object's composition

If doping elements are added to lithium-transition metal oxide, then structural stability is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural stabilityVSAvoidmanufacturing process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent simplifies manufacturing by establishing a clear parameter threshold (FWHM ≤ 0.250) that guides the doping process. This parameter-based approach provides a straightforward control criterion that reduces manufacturing complexity while ensuring structural stability

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 suppresses lattice and crystal structure distortion, reduces gas generation, and improves the lifespan and capacity retention of lithium secondary batteries by maintaining structural stability during lithium ion intercalation/deintercalation.

Implementation Method 1

a FWHM value of a (101) plane peak of the lithium-transition metal oxide particle measured through an in-situ X-ray Diffraction spectroscopy (XRD)

Methodology Applied

Scientific EffectX-ray Diffraction: X-Ray

Data Source

PatentUS20230361291A1Cathode active material for lithium secondary battery and lithium secondary battery including the same

Publication Date: 2023.11.09 SK ON CO LTD

AI summary

A cathode active material for a lithium secondary battery according to an embodiment of the present invention includes a lithium-transition metal oxide particle. The lithium-transition metal oxide particle has a FWHM ratio measured by an in-situ X-ray Diffraction spectroscopy (XRD) and defined by Equation 1 of 400% or less. Life-span properties of a lithium secondary battery can be improved by preventing deformation of a lattice structure and/or a crystal structure in the lithium-transition metal composite oxide particles.