LiAl Composite Oxide Coating for Fast-Charging Lithium-Ion Batteries

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Solution Overview

Problem

Lithium-ion secondary batteries face challenges in achieving high fast charging rates and cycle characteristics due to byproducts generated on the electrode surface during charging and discharging, which affect the density and homogeneity of the coating film of Al-containing oxides.

Innovation Solution

A precursor solution comprising an organic solvent, lithium oxoacid salt, and aluminum compound is used to form a dense and homogeneous LiAl composite oxide coating on active material particles, promoting adhesion and crystal growth at low temperatures, thereby enhancing charge-discharge characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a coating film of Al-containing oxide is provided on lithium cobalt oxide surface, then the electrode characteristics are improved, but the coating film density and homogeneity are insufficient

Engineering Contradiction:

Improveelectrode characteristicsVSAvoidcoating film density and homogeneity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the coating material from pure Al-containing oxide to a composite system containing LiAlO3, Li2SiO3, and Al2O3. This compositional parameter change enables the formation of a denser and more homogeneous coating film that maintains electrode reliability while improving manufacturing precision.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite coating material system comprising LiAlO3, Li2SiO3, and Al2O3 instead of a single Al-containing oxide. This composite material approach creates a multi-phase coating structure that achieves both high density and homogeneity, resolving the contradiction between coating quality and electrode performance.

Inventive Principle:

Principle #40Composite materials

2Productivity

If charging and discharging rate is increased, then fast charging capability is improved, but byproduct generation on electrode surface increases

Engineering Contradiction:

Improvecharging and discharging rateVSAvoidbyproduct generation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent applies a protective coating treatment before the electrode undergoes high-rate charging and discharging cycles. This preliminary coating action prevents byproduct generation during subsequent high-speed operation, allowing the electrode to achieve fast charging capability without suffering from harmful byproduct formation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful byproducts that would normally form during fast charging into beneficial effects by using them as precursors for the protective coating. The coating material system (LiAlO3-Li2SiO3-Al2O3) is designed to form from these byproducts, transforming the harmful accumulation into a protective layer that enhances electrode performance at high rates.

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

The solution enables the production of electrodes with improved charge-discharge performance at high loads by ensuring a dense and homogeneous coating, which is essential for achieving high energy density and long service life in lithium-ion secondary batteries.

Implementation Method 1

a lithium oxoacid salt that shows solubility in the organic solvent; and an aluminum compound that shows solubility in the organic solvent

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

an organic solvent removal step of removing the organic solvent by heating the precursor solution

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 3

a firing step of firing the molded body

Methodology Applied

Scientific EffectFiring: Heat Treatment

Data Source

PatentEP4012797A1Precursor solution, precursor powder, method for producing electrode, and electrode

Publication Date: 2022.06.15 SEIKO EPSON CORP

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AI summary

A precursor solution according to the present disclosure contains an organic solvent, a lithium oxoacid salt that shows solubility in the organic solvent, and an aluminum compound that shows solubility in the organic solvent. When a ratio between a content of aluminum and a content of lithium in a case of satisfying a stoichiometric formulation of the following compositional formula (1) is set as a reference, the content of lithium in the precursor solution is preferably 1.00 times or more and 1.20 times or less with respect to the reference. LiAlO2 (1)