Cubic LLZO Coating for Ni-Rich Cathodes Without High-Temperature Damage

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Ni-rich LiNixMnyCozO2 cathodes exhibit poor cycle life and safety concerns due to interfacial instability with the electrolyte, and existing LLZO coatings require high temperatures and aggressive processes, resulting in amorphous layers with limited Li-ion diffusion.

Innovation Solution

A cubic phase, aluminum-doped lithium lanthanum zirconium oxide (LLZO) coating is applied using flame spray pyrolysis and calcination at low temperatures, forming micron- or sub-micron-sized particles for a uniform, ionically conductive coating on Ni-rich cathodes without damaging the cathode particles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high temperature (at least 1000°C) and aggressive mechanical process are used to reduce LLZO particle size and distribute it on cathode surface, then LLZO coating can be formed, but the cathode particles are substantially damaged and the coating layer becomes amorphous with limited Li-ion diffusion

Engineering Contradiction:

Improvecycle lifeVSAvoidcathode particle damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter from conventional high temperature (≥1000°C) to low temperature (≤700°C) processing. This parameter change enables the formation of crystalline LLZO coating without damaging the cathode particles, resolving the contradiction between forming protective coating and preserving particle integrity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces aggressive mechanical processes with gentle ball milling to achieve uniform distribution of LLZO particles on cathode surface. This substitution eliminates substantial particle damage while still achieving the desired coating distribution, resolving the contradiction between coating formation and particle integrity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If high temperature (at least 1000°C) processing is used to form LLZO coating, then coating can be applied, but the coating layer becomes amorphous with limited Li-ion diffusion coefficient

Engineering Contradiction:

Improvecycle lifeVSAvoidcoating crystallinity and Li-ion diffusion

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent changes the temperature parameter from high (≥1000°C) to low (≤700°C) and maintains it for extended periods (e.g., 12-48 hours). This parameter change enables the formation of crystalline LLZO phase with high Li-ion diffusion coefficient while avoiding amorphous structure, resolving the contradiction between coating formation and coating quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary size reduction of LLZO particles to micron- or sub-micron-sized before coating application. This preliminary action enables uniform coating formation at low temperatures, which in turn enables crystalline phase development without requiring high temperatures, thus resolving the contradiction between coating uniformity and coating crystallinity

Inventive Principle:

Principle #10Preliminary action

3Reliability

If uniform LLZO coating is formed on Ni-rich cathode, then interfacial instability is reduced and cycle life is improved, but processing complexity increases due to low temperature solid state process requirements

Engineering Contradiction:

Improvecycle lifeVSAvoidprocessing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses gentle ball milling to achieve both uniform distribution of LLZO particles and intimate contact with cathode surface simultaneously. This self-service approach achieves multiple objectives (uniform coating, intimate contact, particle integrity) through a single process, reducing overall processing complexity while maintaining high reliability

Inventive Principle:

Principle #25Self-service

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 improves electrochemical performance by enhancing Li-ion diffusion and reducing lithium loss, maintaining the crystal structure of NMC and LLZO, and achieving a stable, thin coating that improves energy density and cycle life.

Implementation Method 1

flame spray pyrolysis

Methodology Applied

Scientific EffectPyrolysis: Pyrolysis

Implementation Method 2

flame spray pyrolysis

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

calcined at low temperature (i.e., less than 700° C.) to achieve the electrochemically preferred, ionically conductive cubic phase

Methodology Applied

Scientific EffectPhase transition: Phase Change

Implementation Method 4

allows a uniform coating to be formed on the NMC materials via gentle ball milling that does not substantially damage the cathode particles

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Implementation Method 5

ionically conductive cubic phase

Methodology Applied

Scientific EffectIonic conduction: Conduction (electrical)

Data Source

PatentUS11821091B2Solvent-free processing of lithium lanthanum zirconium oxide coated-cathodes

Publication Date: 2023.11.21 UCHICAGO ARGONNE LLC

AI summary

A dry process for coating Ni-rich cathode powder with cubic LLZO powder prepared by flame spray pyrolysis.