Lithium Transition Metal Oxide Coating for Battery Rate and Stability

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Solution Overview

Problem

Lithium transition metal oxides used in cathode active materials for lithium secondary batteries suffer from low electrical conductivity and insufficient charge-discharge rate properties due to low ionic conductivity, and increasing energy density poses safety risks such as ignition and explosion.

Innovation Solution

A cathode active material is developed by coating lithium transition metal oxide with carbon particles and a polymer resin, where the polymer resin is inactivated by an electrolyte and organic solvent, providing high electrical and ionic conductivity, and maintaining high temperature stability by preventing ion and electron mobility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If lithium transition metal oxide is used as cathode active material, then high energy density is achieved, but low electrical conductivity and insufficient charge-discharge rate properties occur

Engineering Contradiction:

Improveenergy densityVSAvoidcharge-discharge rate properties

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent applies a composite coating structure consisting of carbon particles and polymer resin on the lithium transition metal oxide surface. The carbon particles provide electrical conductivity while the polymer resin matrix binds the particles and provides ionic conductivity, creating a composite material that simultaneously improves both electrical conductivity and charge-discharge rate properties while maintaining high energy density.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The coating is applied specifically to the surface of the lithium transition metal oxide particles rather than throughout the bulk material. This local modification preserves the high energy density properties of the core lithium transition metal oxide while improving the surface conductivity and interfacial properties to enhance charge-discharge rate.

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If energy density is increased, then battery performance is improved, but safety risks such as ignition and explosion increase

Engineering Contradiction:

Improveenergy densityVSAvoidignition and explosion risks

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The polymer resin acts as an intermediary layer between the lithium transition metal oxide and the electrolyte. It modifies the interfacial properties to improve ionic conductivity while also providing thermal stability and preventing direct contact between reactive components, thereby reducing safety risks associated with high energy density batteries.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potential harm of high reactivity at the electrode-electrolyte interface into a benefit by using the polymer resin to create a stable interfacial layer. This layer prevents harmful side reactions and thermal runaway while maintaining good ionic conductivity, thus converting the safety risk into improved battery performance and safety.

Inventive Principle:

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

3Reliability

If conventional coating methods are applied to improve conductivity, then contact resistance decreases, but side products generated at high temperature and insufficient cell characteristics occur

Engineering Contradiction:

Improveelectrical conductivityVSAvoidside products at high temperature

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical and physical parameters of the coating by using a polymer resin with specific properties (melting point of at least 80°C, inactivation by electrolyte and organic solvent). These parameter changes ensure the coating remains stable at high temperatures, prevents side product formation, and maintains good electrical and ionic conductivity throughout battery operation.

Inventive Principle:

Principle #35Parameter changes

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

The solution enhances rate properties and high temperature stability, reducing the risk of battery ignition and explosion while maintaining performance, as the carbon particles improve conductivity and the polymer resin increases internal resistance at high temperatures.

Implementation Method 1

carbon particles and a polymer resin at a surface thereof, and the polymer resin is inactivated by an electrolyte for lithium secondary batteries

Methodology Applied

Scientific EffectElectrical conductivity enhancement: Conduction (electrical)

Implementation Method 2

the polymer resin is inactivated by an electrolyte for lithium secondary batteries and an organic solvent and has a melting point of at least 80° C.

Methodology Applied

Scientific EffectThermal resistance: Thermal Insulation

Data Source

PatentUS9325011B2Cathode active material for lithium secondary battery

Publication Date: 2016.04.26 LG ENERGY SOLUTION LTD

AI summary

Disclosed herein is a cathode active material for a lithium secondary battery, including lithium transition metal oxide, where the lithium transition metal oxide is coated with carbon particles and a polymer resin at a surface thereof, and the polymer resin is a substance inactivated by an electrolyte for a lithium secondary battery and an organic solvent and has a melting point of at least 80° C. A lithium secondary battery having the disclosed cathode active material has advantages of improving rate properties and high temperature stability, so as to provide excellent cell characteristics.