Ni-Rich Cathode Composition for Better Battery Cycle Stability

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Solution Overview

Problem

Lithium-transition metal composite oxides with high Ni content used in non-aqueous electrolyte secondary batteries face capacity degradation due to layered crystal structure collapse during charge-discharge cycles, and existing solutions do not adequately improve charge-discharge cycle characteristics.

Innovation Solution

Incorporating specific amounts of Ca and Al into the lithium-transition metal composite oxide, with Ca present on the particle surface and Al substituting in the transition metal layer, stabilizes the Li layer and transition metal layer, resulting in improved cycle characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a lithium-transition metal composite oxide with high Ni content is used as positive electrode active material, then energy density is improved, but charge-discharge cycle characteristics deteriorate due to layered crystal structure collapse

Engineering Contradiction:

Improveenergy densityVSAvoidcharge-discharge cycle characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies local quality by introducing metal elements (Al, Ca, and others) at specific locations within the crystal structure - primarily in the Li layer and transition metal layer - to locally stabilize the structure without changing the overall high-Ni composition. This localized modification prevents structure collapse during charge-discharge cycles while maintaining high energy density.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs composite materials by combining Ni-rich lithium-transition metal composite oxide with specific amounts of metal elements (Al: 0.01-0.08 mol%, Ca: 0.005-0.02 mol%, and others). This composite approach creates a multi-element system where the additional elements work synergistically to stabilize the crystal structure while preserving the high-capacity characteristics of Ni-rich materials.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If Li is extracted during charge from high Ni content composite oxide, then capacity is improved, but layered structure collapses with repeated cycles

Engineering Contradiction:

ImproveLi extraction capacityVSAvoidlayered crystal structure stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by pre-introducing metal elements (Al, Ca, etc.) into the crystal structure before charge-discharge cycling begins. These elements are positioned in advance in the Li layer and transition metal layer to prevent structure collapse during subsequent Li extraction and insertion cycles, enabling high capacity while maintaining structural integrity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements beforehand cushioning by incorporating metal elements that act as structural buffers within the crystal lattice. These elements cushion against the mechanical stress and structural degradation that would otherwise occur during repeated Li extraction and insertion, allowing high Li extraction capacity while maintaining layered structure stability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If metal elements are added to stabilize Li layer and transition metal layer, then charge-discharge cycle characteristics are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvecharge-discharge cycle characteristicsVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the composition parameters of metal elements within narrow ranges (Al: 0.01-0.08 mol%, Ca: 0.005-0.02 mol%). This parameter optimization achieves effective structure stabilization while minimizing manufacturing complexity, as the controlled composition ranges enable straightforward synthesis processes without requiring complex multi-step procedures.

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 stabilization of the Li and transition metal layers, along with the particle surface, significantly enhances the charge-discharge cycle characteristics of the battery, preventing erosion and maintaining capacity.

Implementation Method 1

Al substituting in the transition metal layer, stabilizes the Li layer and transition metal layer

Methodology Applied

Scientific EffectSubstitution:

Data Source

PatentEP4037029B1Positive electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Publication Date: 2024.02.21 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

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AI summary

A positive electrode active material for a non-aqueous electrolyte secondary battery, according to an example of this embodiment, includes a lithium transition metal composite oxide which has a layered structure and contains at least Ni, Al, and Ca. The lithium transition metal composite oxide has a Ni content of 85-95 mol%, an Al content of at most 8 mol%, and a Ca content of at most 2 mol% with respect to the total amount of metal elements other than Li. In addition, the proportion of metal elements other than Li present in a Li layer is 0.6-2.0 mol% with respect to the total amount of metal elements other than Li contained in the composite oxide.