Amorphous Lithium Coatings for Cathode Ionic Conductivity
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Solution Overview
Problem
Existing methods for coating transition metal oxides as cathode materials in lithium-ion batteries, such as wet coating and Atomic Layer Deposition, are laborious and result in crystalline coatings that do not effectively improve cycling performance and discharge capacity due to reduced ionic conductivity.
Innovation Solution
A method involving dry mixing of transition metal oxides with an amorphous lithium-containing powder, comprising metals like niobium, aluminum, titanium, zirconium, silicon, or tungsten, followed by sintering, to create a coated transition metal oxide that enhances cycling performance and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet coating or Atomic Layer Deposition methods are used to coat transition metal oxides, then the coating process can be performed, but the process becomes laborious and the resulting crystalline coating reduces ionic conductivity
Solution Approach 1:
The patent changes the physical state parameter of the coating from crystalline to amorphous, which fundamentally alters the ionic conductivity properties. By controlling the coating formation to produce an amorphous lithium-containing phase rather than a crystalline one, the patent achieves high ionic conductivity while simplifying the coating process to a straightforward mixing and sintering procedure, eliminating the need for complex wet coating or atomic layer deposition techniques
Solution Approach 2:
The patent employs a composite coating structure consisting of amorphous lithium-containing compounds combined with metal oxides (such as niobium oxide, aluminum oxide, titanium oxide, zirconium oxide, silicon oxide, or tungsten oxide). This composite approach creates a synergistic effect where the amorphous lithium phase provides high ionic conductivity while the metal oxide component enhances structural stability and chemical compatibility with the transition metal oxide core, thereby improving cycling performance without increasing process complexity
2Reliability
If crystalline coating is formed on transition metal oxide, then the coating structure is stable, but the ionic conductivity is reduced
Solution Approach 1:
The patent fundamentally changes the structural parameter from crystalline to amorphous, which eliminates the long-range order of crystalline structures while maintaining short-range order. This amorphous state allows for continuous pathways for lithium ion diffusion, achieving high ionic conductivity. The stability is maintained through the chemical composition and bonding within the amorphous phase, rather than relying on crystalline lattice structures
Solution Approach 2:
The composite nature of the coating, combining amorphous lithium-containing compounds with metal oxides, provides both the ionic conductivity needed for performance and the structural stability required for durability. The metal oxide component forms a stable framework that supports the amorphous lithium phase, preventing unwanted phase transformations during cycling while allowing efficient ion transport
3Reliability
If surface coating is applied to suppress direct contact between active material and electrolyte, then aging is reduced, but the coating material must balance multiple properties
Solution Approach 1:
The amorphous lithium-containing coating with metal oxides serves multiple functions simultaneously: it acts as a protective barrier between the active material and electrolyte to suppress aging and improve cycle life, provides high ionic conductivity to maintain performance, and offers chemical compatibility with various transition metal oxide cores. This multi-functional coating reduces the need to optimize different coating materials for different applications, as the same amorphous lithium-metal oxide composite structure can be universally applied to protect various cathode materials
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 amorphous lithium-containing coating improves the cycling performance and discharge capacity of lithium-ion batteries by maintaining high ionic conductivity and reducing electrochemical degradation.
Implementation Method 1
This high ionic conductivity can be improved by coating the surface of an active electrode material by certain lithium-comprising compounds... The amorphous phase that includes a mixture of lithium oxide and tungsten oxide
Implementation Method 2
Surface coating has proven to be an extremely important method to address this aging problem of CAMs by suppressing the direct contact between the active materials surfaces and the electrolyte
Implementation Method 3
A method involving dry mixing of transition metal oxides with an amorphous lithium-containing powder, comprising metals like niobium, aluminum, titanium, zirconium, silicon, or tungsten
Implementation Method 4
followed by sintering, to create a coated transition metal oxide that enhances cycling performance and discharge capacity
Data Source
AI summary
The present invention relates to a method for making a transition metal oxide coated with an at least partially amorphous lithium-containing coating and a method for making an at least partially amorphous lithium-containing powder as well as the coated transition metal oxide and the lithium-containing powder obtainable by these methods. The present invention further relates to an electrode, electrolyte, or energy-storage device, such as a lithium-ion solid-state battery, comprising the coated transition metal oxide.