High-Ni Cathode Material Mixing Aggregated Particles for Lower Resistance

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Solution Overview

Problem

Non-aqueous electrolyte secondary batteries with composite oxide particles containing Ni, Co, and Li, and having a proportion of Ni of 80 mol % or more, face challenges in maintaining battery capacity and reducing direct current resistance when the particles are in a non-aggregated state, as they tend to have reduced discharge capacity and increased resistance.

Innovation Solution

The use of composite oxide particles with a proportion of Ni at 80 mol % or more, composed of both aggregated and non-aggregated states in a specific mass ratio (5:95 to 50:50), which enhances battery capacity and reduces direct current resistance by allowing deeper discharge and improved electrochemical interactions between particle states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If composite oxide particles are in a non-aggregated state, then charge and discharge cycle characteristics are satisfactory, but battery capacity is reduced

Engineering Contradiction:

Improvecharge and discharge cycle characteristicsVSAvoidbattery capacity

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The positive electrode active material is segmented into two distinct particle state populations: aggregated particles (providing high capacity) and non-aggregated particles (providing good cycle characteristics). This segmentation allows each population to fulfill its specific functional role without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the aggregation state parameter of the composite oxide particles from a uniform non-aggregated state to a mixed state containing both aggregated and non-aggregated particles. By controlling the mass ratio parameter (5:95 to 50:50), the invention optimizes the balance between battery capacity and cycle characteristics.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If composite oxide particles are in a non-aggregated state, then charge and discharge cycle characteristics are satisfactory, but direct current resistance is high

Engineering Contradiction:

Improvecharge and discharge cycle characteristicsVSAvoiddirect current resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The positive electrode active material is segmented into two distinct particle state populations: aggregated particles (providing low resistance) and non-aggregated particles (providing good cycle characteristics). This segmentation allows each population to fulfill its specific functional role without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #35Parameter changes

3Power

If high Ni proportion (80 mol % or more) is used in composite oxide, then output improvement is desired, but battery capacity is reduced

Engineering Contradiction:

ImproveoutputVSAvoidbattery capacity

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

Different regions (aggregated vs. non-aggregated particles) have different local qualities: aggregated particles provide high conductivity and power output, while non-aggregated particles provide good cycle stability. The high Ni proportion (80 mol % or more) is distributed across both particle types, allowing each to contribute its specific advantage.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention creates a composite structure at the particle level by combining aggregated and non-aggregated composite oxide particles in specific mass ratios. This composite approach allows the high Ni content material to deliver both high power output and adequate battery capacity by leveraging the complementary properties of the two particle states.

Inventive Principle:

Principle #40Composite materials

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

This configuration improves battery capacity and reduces direct current resistance by enabling deeper discharge and enhanced electrochemical interactions, resulting in more efficient energy storage and utilization.

Implementation Method 1

charging and discharging is conducted by migration of lithium ions between the positive electrode and the negative electrode

Methodology Applied

Scientific EffectIon migration: Diffusion

Data Source

PatentUS11742480B2Positive electrode active material for nonaqueous electrolyte secondary batteries, and nonaqueous electrolyte secondary battery

Publication Date: 2023.08.29 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

This positive electrode active material for nonaqueous electrolyte secondary batteries comprises composite oxide particles which contain Ni, Co and Li, while containing at least one of Mn and Al, and wherein the ratio of Ni to the total number of moles of the metal elements other than Li is 80% by mole or more. The composite oxide particles are composed of particles in an aggregated state and particles in a non-aggregated state; and the content ratio of the particles in an aggregated state to the particles in a non-aggregated state is from 5:95 to 50:50 in terms of the mass ratio.