Nonaqueous Secondary Battery Electrode Composition for Cycle Stability

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Solution Overview

Problem

Lithium-transition metal composite oxides with high Ni content and low Co content have unstable structures, leading to side reactions with electrolytes that deteriorate charge-discharge cycle characteristics in non-aqueous electrolyte secondary batteries.

Innovation Solution

A non-aqueous electrolyte secondary battery using a lithium-transition metal composite oxide with specific compositions of Ni, Nb, and M (Ca or Sr) as positive electrode active material, and a coating of Nb and M on the negative electrode surface to inhibit structural deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the Co content is reduced in high Ni content lithium-transition metal composite oxide, then the cost is reduced, but the structure stability deteriorates leading to increased side reactions with electrolyte

Engineering Contradiction:

ImproveCo contentVSAvoidstructure stability

Core Design Contradiction:

Quantity of substanceVSStability of the object's composition

Solution Approach 1:

Nb and M (Ca or Sr) are introduced as intermediary elements that mediate between the high Ni content and structure stability. These elements act as structural stabilizers that prevent the composite oxide from undergoing harmful side reactions with the electrolyte, thereby protecting the overall structure while allowing reduced Co content

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite material system by combining Ni, Nb, M (Ca or Sr), and Co in specific ratios. This composite approach allows the synergistic effect where Nb and M compensate for the structural instability caused by high Ni content and low Co content, achieving both cost reduction and structure stability

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If high Ni content lithium-transition metal composite oxide is used, then the energy density is improved, but the charge-discharge cycle characteristics deteriorate due to structure instability

Engineering Contradiction:

Improveenergy densityVSAvoidcharge-discharge cycle characteristics

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent changes the compositional parameters of the composite oxide by introducing Nb and M elements with specific content ratios (Nb: 0.01-0.35 mol%, M: 0.01-0.5 mol%). These parameter changes stabilize the crystal structure, preventing degradation during charge-discharge cycles while maintaining high Ni content for energy density

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Nb and M serve as intermediary elements that protect the high Ni content composite oxide from structural degradation. They act as stabilizing agents that prevent the formation of harmful phases and reduce side reactions with electrolyte, thereby improving cycle life without sacrificing energy density

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If high Ni content and low Co content composite oxide is used, then the manufacturing cost is reduced, but the capacity loss increases due to side reactions with electrolyte

Engineering Contradiction:

Improvemanufacturing costVSAvoidcapacity loss

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent converts the potential harm of high Ni content and low Co content (which would lead to structure instability and capacity loss) into a benefit by strategically introducing Nb and M elements. These elements transform the unstable structure into a stable one, turning what would be a detrimental composition into a beneficial, stable, and cost-effective material

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12573623B2Nonaqueous electrolyte secondary battery

Publication Date: 2026.03.10 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A nonaqueous electrolyte secondary battery according to one embodiment of the present disclosure is provided with a positive electrode, a negative electrode and a nonaqueous electrolyte; the positive electrode contains a lithium transition metal composite oxide that contains Ni, Nb and M (M is at least one element selected from among Ca and Sr), said lithium transition metal composite oxide optionally containing Co; the contents of Ni, Nb, M and Co in the lithium transition metal composite oxide are respectively within specific ranges; the negative electrode comprises a negative electrode mixture layer that contains a negative electrode active material, and a coating film that is formed on the surface of the negative electrode mixture layer, while containing Nb and M; and the contents of Nb and M in the negative electrode are respectively within specific ranges.