Porous Lithium Composite Oxide Cathode Coating for Low-Resistance Batteries

Solution Overview

Problem

Nonaqueous electrolyte secondary batteries, such as lithium ion batteries, face challenges in reducing resistance to enhance capacity and output, particularly when using lithium composite oxides with a layered structure as positive electrode active materials.

Innovation Solution

The battery incorporates lithium composite oxide particles with a layered structure, coated with lithium tungstate, where the particles have a porous structure with voids connecting to the surface and an opening diameter of at least 100 nm, and an average void ratio of 10% to 50%, with a granular lithium tungstate coating having a smaller particle diameter than the void openings, to reduce resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lithium composite oxide with layered structure is used as positive electrode active material, then battery capacity is improved, but battery resistance increases

Engineering Contradiction:

Improvebattery capacityVSAvoidbattery resistance

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies porous materials by forming lithium composite oxide particles with a porous structure containing voids that have openings to the particle surface. The porous structure increases the surface area for ion conduction while maintaining the high capacity of the layered lithium composite oxide material, thereby reducing battery resistance without sacrificing capacity.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent applies the nesting principle by coating the porous lithium composite oxide particles with lithium tungstate. The lithium tungstate coating is formed within and on the porous structure, creating a nested configuration where the coating material is embedded in the porous particle structure. This nested arrangement provides conductive pathways through the porous structure while protecting the active material.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Power

If lithium tungstate coating is applied on lithium composite oxide surface, then battery output is improved, but battery resistance remains high

Engineering Contradiction:

Improvebattery outputVSAvoidbattery resistance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent applies porous materials by forming lithium composite oxide particles with a porous structure containing voids that have openings to the particle surface. The porous structure increases the surface area for ion conduction while maintaining the high capacity of the layered lithium composite oxide material, thereby reducing battery resistance without sacrificing capacity.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The patent applies the nesting principle by coating the porous lithium composite oxide particles with lithium tungstate. The lithium tungstate coating is formed within and on the porous structure, creating a nested configuration where the coating material is embedded in the porous particle structure. This nested arrangement provides conductive pathways through the porous structure while protecting the active material.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 significantly reduces battery resistance and increases output by promoting ion conduction and increasing the surface area for the lithium tungstate coating, resulting in improved performance for nonaqueous electrolyte secondary batteries.

Implementation Method 1

Each of the porous particles has a void that connects an interior of each of the particles to a surface thereof and has an opening. The opening has an opening diameter of at least 100 nm.

Methodology Applied

Scientific EffectIon conduction: Conduction (electrical)

Implementation Method 2

Each of the porous particles is provided with a coating of lithium tungstate on their surface.

Methodology Applied

Scientific EffectSurface coating: Coatings

Data Source

PatentUS11923534B2Nonaqueous electrolyte secondary battery including a positive electrode active substance containing a lithium composite oxide porous particle having voids

Publication Date: 2024.03.05 TOYOTA JIDOSHA KK

AI summary

A non-aqueous electrolyte secondary battery which is obtained using a lithium composite oxide having a layered structure and coated with a tungsten-containing compound in a positive electrode active substance, and which has a low initial resistance, and in which an increase in resistance following repeated charging and discharging is suppressed. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode and a non-aqueous electrolyte. The positive electrode includes a positive electrode active substance layer containing a lithium composite oxide having a layered structure. The lithium composite oxide includes a porous particle having a void ratio of not less than 20% but not more than 50%. The porous particle contains two or more voids having diameters that are at least 10% of the particle diameter of the porous particle. The surface of the porous particle is provided with a coating containing tungsten oxide and lithium tungstate.