Cathode Coating and Electrolyte Pairing for Stable Secondary Batteries

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Solution Overview

Problem

Existing secondary batteries face challenges in securely managing the entry and exit of lithium and in suppressing the decomposition reaction of the electrolytic solution, which affects battery performance and longevity.

Innovation Solution

A secondary battery configuration that includes a positive electrode with layered rock-salt lithium composite oxide and spinel metal oxide, along with an electrolytic solution containing a chain carboxylic acid ester and a cyclic ether, which together enhance lithium management and reduce electrolytic solution decomposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a layered rock-salt lithium composite oxide is used as the positive electrode active material, then the energy density and battery capacity are improved, but the decomposition reaction of the electrolytic solution increases and lithium entry/exit is not sufficiently secured

Engineering Contradiction:

Improvebattery capacityVSAvoidelectrolytic solution stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

A spinel metal oxide coating layer is introduced as an intermediary between the layered rock-salt lithium composite oxide and the electrolytic solution. This coating layer suppresses the decomposition reaction of the electrolytic solution while maintaining lithium entry and exit, thereby resolving the contradiction between battery capacity and electrolytic solution stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The positive electrode active material is designed as a composite structure combining layered rock-salt lithium composite oxide with spinel metal oxide coating. This composite material approach enables the core to provide high capacity while the coating provides stability and protection against electrolytic solution decomposition.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the positive electrode active material surface is coated to suppress electrolytic solution decomposition, then the electrolytic solution stability is improved, but lithium entry and exit may be hindered

Engineering Contradiction:

Improveelectrolytic solution stabilityVSAvoidlithium entry and exit efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The spinel metal oxide coating is designed with specific compositional parameters (X3O4 where X includes cobalt, aluminum, magnesium, or zinc) and thickness control to maintain lithium ion conductivity. By optimizing these parameters, the coating suppresses electrolytic solution decomposition while allowing efficient lithium entry and exit.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If nickel content in the positive electrode active material is increased to improve energy density, then the battery capacity is improved, but nickel elution into the electrolyte increases

Engineering Contradiction:

Improvebattery capacityVSAvoidnickel elution

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The spinel metal oxide coating, which may contain nickel, is designed to prevent nickel elution into the electrolytic solution. The coating structure converts the potential harm of nickel content into a benefit by containing nickel within the stable spinel structure while allowing lithium ion transport, thus suppressing nickel elution while maintaining high capacity.

Inventive Principle:

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

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 effectively secures lithium entry and exit while suppressing electrolytic solution decomposition, leading to improved battery characteristics such as increased load retention and cycle retention rates, and reduced swelling.

Implementation Method 1

The positive electrode active material particle has therein the spinel metal oxide provided on at least a surface of the layered rock-salt lithium composite oxide

Methodology Applied

Scientific EffectSurface coating protection:

Implementation Method 2

the electrolytic solution includes a chain carboxylic acid ester and a cyclic ether

Methodology Applied

Scientific EffectIon transport:

Data Source

PatentUS12230796B2Secondary battery

Publication Date: 2025.02.18 MURATA MFG CO LTD

AI summary

A secondary battery includes a positive electrode, a negative electrode, and an electrolytic solution. The positive electrode includes a positive electrode active material particle. The positive electrode active material particle includes a layered rock-salt lithium composite oxide and a spinel metal oxide. The positive electrode active material particle has therein the spinel metal oxide provided on at least a surface of a particle including the layered rock-salt lithium composite oxide. The electrolytic solution includes a chain carboxylic acid ester and a cyclic ether.