Dry-Coated NMC Cathodes With Lithium Titanate-Aluminate Shells

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Solution Overview

Problem

Existing lithium ion batteries face rapid aging and performance loss due to electrochemical degradation mechanisms in cathode materials, particularly nickel manganese cobalt mixed oxides (NMC), leading to decreased capacity and cycle life, with existing coatings either failing to improve ionic conductivity or causing lattice distortion.

Innovation Solution

A dry coating process using pyrogenically produced lithium titanate and/or lithium aluminate is applied to transition metal oxides, ensuring homogeneous distribution and adherence without the use of solvents, maintaining ionic conductivity and enhancing long-life stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If transition metal oxide cathode materials are used to achieve high energy density, then battery energy storage capacity is improved, but rapid aging and performance loss occur due to electrochemical degradation mechanisms

Engineering Contradiction:

Improvebattery energy densityVSAvoidcathode stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent applies composite materials by coating transition metal oxide particles with a dual-layer structure consisting of lithium aluminate (inner layer) and lithium titanate (outer layer). This composite structure combines the high energy density properties of NMC cathodes with the protective and conductive properties of the coating layers, resolving the contradiction between energy density and stability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent implements local quality by applying functional coatings specifically at the particle surface level rather than bulk modification. The inner lithium aluminate layer provides local protection against electrolyte attack, while the outer lithium titanate layer provides local enhancement of ionic conductivity at the critical electrode-electrolyte interface, addressing degradation without compromising bulk energy density.

Inventive Principle:

Principle #3Local quality

2Reliability

If metal oxide coatings are applied to improve long-term cycling stability, then cathode protection is enhanced, but ionic conductivity decreases leading to lower initial currents

Engineering Contradiction:

Improvecycling stabilityVSAvoidionic conductivity loss

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent uses local quality by creating a differentiated two-layer coating structure where each layer performs a specific function. The inner lithium aluminate layer provides local chemical protection, while the outer lithium titanate layer provides local ionic conductivity enhancement at the electrode surface, ensuring both protection and conductivity are optimized at their respective locations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies composite materials by combining lithium aluminate and lithium titanate in a layered structure. This composite approach allows the material to simultaneously exhibit protective characteristics from lithium aluminate and high ionic conductivity from lithium titanate, resolving the contradiction between stability and conductivity.

Inventive Principle:

Principle #40Composite materials

3Manufacturing precision

If conventional wet coating methods are used to apply protective coatings, then coating homogeneity is improved, but solvent residues and additional processing steps are introduced

Engineering Contradiction:

Improvecoating homogeneityVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the solvent component from the conventional wet coating process, adopting a dry mixing approach. This removes the need for solvent evaporation steps and reduces processing complexity while maintaining coating homogeneity through direct mechanical mixing of the coating materials with the cathode particles.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the chemical-based wet coating mechanism with a mechanical dry mixing process. Instead of using solvents and chemical deposition, the coating is applied through mechanical dispersion and mixing, simplifying the overall process while achieving uniform distribution of coating materials.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 coated transition metal oxides exhibit improved cycling performance and stability, maintaining initial discharge capacities and extending cycle life without compromising ionic conductivity, suitable for both liquid and solid-state electrolytes.

Implementation Method 1

pyrogenically produced lithium titanate and/or pyrogenically produced lithium aluminate

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Data Source

PatentUS12142761B2Transition metal oxide particles encapsulated in nanostructured lithium titanate or lithium aluminate, and the use thereof in lithium ion batteries

Publication Date: 2024.11.12 EVONIK OPERATIONS GMBH

AI summary

A process for producing a coated transition metal oxide involves subjecting a transition metal oxide and a pyrogenically produced lithium titanate and/or pyrogenically produced lithium aluminate to dry mixing. A coated transition metal oxide is obtainable by this process; and cathode for a lithium ion battery and a lithium ion battery containing such coated particles is useful.