Layered-Spinel Composite Cathode for Safe High-Density Batteries

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Solution Overview

Problem

Nonaqueous electrolyte secondary batteries face challenges in achieving high energy density and improved cycle characteristics while maintaining safety, as existing positive electrode active materials with high energy density tend to have unsatisfactory safety due to oxygen releasability issues during charging and high-temperature conditions.

Innovation Solution

A positive electrode active material composed of a composite oxide containing lithium, nickel, and manganese, with aggregated particles having an average diameter of 1.0 μm or more, featuring a layered crystal structure and spinel crystal structure, produced through a two-stage firing process to reduce oxygen releasability and enhance durability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a positive electrode active material with high energy density is used, then the battery capacity is improved, but the safety deteriorates due to oxygen releasability issues

Engineering Contradiction:

Improveenergy densityVSAvoidsafety

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by combining layered crystal structure and spinel crystal structure within the same positive electrode active material particles. This composite structure integrates the high capacity characteristics of layered structures with the thermal stability and suppressed oxygen releasability of spinel structures, thereby achieving both high energy density and improved safety

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating regions with different crystal structures within the positive electrode active material. The layered crystal structure provides high capacity in certain regions, while the spinel crystal structure provides thermal stability and oxygen suppression in other regions, allowing the material to exhibit both high energy density and improved safety characteristics simultaneously

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the filling property of positive electrode active material is increased, then the energy density is improved, but the oxygen releasability increases causing safety issues

Engineering Contradiction:

Improvefilling densityVSAvoidoxygen releasability

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The composite crystal structure combines the high filling density capability of layered structures with the oxygen suppression特性 of spinel structures, allowing increased filling property without proportional increase in oxygen releasability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the crystal structure parameters by introducing spinel phase into the layered structure, which fundamentally alters the oxygen release behavior while maintaining high filling density capability

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10573881B2Positive electrode active material for nonaqueous electrolyte secondary battery

Publication Date: 2020.02.25 PANASONIC HOLDINGS CORP

AI summary

A positive electrode active material for a nonaqueous electrolyte secondary battery is used for a nonaqueous electrolyte secondary battery. The positive electrode active material includes a composite oxide containing at least lithium, nickel, and manganese and contains aggregated particles of primary particles having an average particle diameter of 1.0 μm or more. The primary particles have a layered crystal structure and a spinel crystal structure.