High-Ni Cathode Active Material With Stable Layered Structure

Solution Overview

Problem

Existing positive electrode active materials for non-aqueous electrolyte secondary batteries face instability in their layered structure when the proportion of Ni to the total number of metal elements excluding Li is 85 mol % or more and Co is 10 mol % or less, leading to increased reaction resistance.

Innovation Solution

A lithium composite oxide with a layered structure, represented by LiaNiαAlβCoγMδSrxO2-w, where 0.95<a<1.05, 0.85≤α≤0.95, 0<β≤0.08, 0≤γ≤0.1, 0≤δ≤0.15, 0<x≤0.015, and M includes elements like Mn, Fe, Ti, Si, Nb, Zr, Mo, and Zn, is used, with metal elements other than Li present in the Li layer in a range of 1 to 2.5 mol % to stabilize the structure and reduce reaction resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the proportion of Ni is increased to 85 mol % or more to obtain high discharge capacity, then the discharge capacity is improved, but the layered structure becomes unstable and reaction resistance increases

Engineering Contradiction:

Improvedischarge capacityVSAvoidlayered structure stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies local quality by introducing Al and Sr elements at specific local positions within the lithium composite oxide structure. Al is incorporated into the layered structure to stabilize it, while Sr is added to the surface to modify surface state and reduce reaction resistance. This localized modification allows high Ni content (85 mol % or more) to be maintained for high capacity while preventing the instability that would normally result from such high Ni content.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite material system by combining Li, Ni, Al, Co, Sr, and O elements in a specific composite oxide structure (LiaNiαAlβCoγMδSrxO2-w). This composite approach allows the material to benefit from Ni's high capacity while Al provides structural stability and Sr provides surface modification, thereby resolving the contradiction between high capacity and structural stability.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If the proportion of Co is reduced to 10 mol % or less to reduce production cost, then the production cost is improved, but the layered structure becomes unstable and reaction resistance increases

Engineering Contradiction:

Improveproduction costVSAvoidlayered structure stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by introducing Al and Sr elements at specific local positions within the lithium composite oxide structure. Al is incorporated into the layered structure to stabilize it, while Sr is added to the surface to modify surface state and reduce reaction resistance. This localized modification allows high Ni content (85 mol % or more) to be maintained for high capacity while preventing the instability that would normally result from such high Ni content.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite material system by combining Li, Ni, Al, Co, Sr, and O elements in a specific composite oxide structure (LiaNiαAlβCoγMδSrxO2-w). This composite approach allows the material to benefit from Ni's high capacity while Al provides structural stability and Sr provides surface modification, thereby resolving the contradiction between high capacity and structural stability.

Inventive Principle:

Principle #40Composite materials

3Quantity of substance

If the proportion of Ni is increased to 85 mol % or more to obtain high discharge capacity, then the discharge capacity is improved, but the reaction resistance increases

Engineering Contradiction:

Improvedischarge capacityVSAvoidreaction resistance

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by introducing Al and Sr elements at specific local positions within the lithium composite oxide structure. Al is incorporated into the layered structure to stabilize it, while Sr is added to the surface to modify surface state and reduce reaction resistance. This localized modification allows high Ni content (85 mol % or more) to be maintained for high capacity while preventing the instability that would normally result from such high Ni content.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses Sr as an intermediary element that mediates between the high-Ni bulk material and the electrolyte. Sr modifies the surface state of the lithium composite oxide, creating an intermediate layer that reduces reaction resistance while allowing the high-Ni composition to maintain its high capacity characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12597603B2Cathode active material for non-aqueous-electrolyte secondary battery and non-aqueous-electrolyte secondary battery

Publication Date: 2026.04.07 PANASONIC ENERGY CO LTD

AI summary

Provided is a cathode active material for a non-aqueous-electrolyte secondary battery, the cathode active material containing a lithium composite oxide that has a layered structure containing a Li layer and that is represented by general formula LiaNiαAlβCoγMδSrxO2-w (in the formula, 0.95<a<1.05, 0.85≤α≤0.95, 0<β≤0.08, 0≤γ≤0.1, 0≤δ≤0.15, 0<x≤0.015, 0≤w<0.05, α+β+γ+δ=1, and M is at least one type of element selected from Mn, Fe, Ti, Si, Nb, Zr, Mo, and Zn), wherein the proportions of metal elements present in the Li layer excluding Li are in the range of 1-2.5 mol % with respect to the total molar quantity of metal elements in the lithium composite oxide excluding Li.