Amorphous Lithium-Containing Coatings for Stable Cathode Cycling
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Solution Overview
Problem
Existing methods for coating transition metal oxides used in cathode materials for lithium-ion batteries often result in crystalline coatings, which can reduce ionic conductivity and lead to degradation, affecting the cycling performance and discharge capacity of energy-storage devices.
Innovation Solution
A method involving dry mixing of transition metal oxides with an at least partially amorphous lithium-containing powder, comprising lithium and metals like niobium, aluminum, or titanium, followed by sintering, to create a coated transition metal oxide that improves cycling performance and discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If transition metal oxide is coated with a crystalline lithium-containing coating through calcination, then the coating provides structural stability, but the ionic conductivity decreases and cycling performance deteriorates
Solution Approach 1:
The patent changes the thermal processing parameters by using low-temperature treatment (≤500°C) instead of high-temperature calcination, and controls the heating rate and holding time to prevent crystallization. This parameter change maintains the amorphous state of the coating, preserving ionic conductivity while providing structural stability through the amorphous lithium-containing phase.
Solution Approach 2:
The patent creates a composite coating structure combining amorphous lithium-containing phase with transition metal oxide core. The amorphous lithium-containing compound (such as lithium phosphate, lithium sulfate, or lithium selenate) forms a composite material that provides both structural stability and high ionic conductivity, resolving the contradiction between stability and reliability.
2Stability of the object's composition
If transition metal oxide is coated with a crystalline lithium-containing coating, then the coating forms a stable surface layer, but the discharge capacity decreases
Solution Approach 1:
The patent changes the coating formation parameters by using low-temperature processing (≤500°C) and controlling the atmosphere to maintain amorphous structure. This prevents the formation of crystalline phases that would block lithium ion diffusion pathways, thereby preserving discharge capacity while still forming a stable surface layer.
Solution Approach 2:
The patent creates a coating with localized amorphous structure that provides different properties at different scales: at the macro level, it forms a stable surface layer protecting the core material, while at the micro level, the amorphous structure maintains open channels for lithium ion transport, ensuring high discharge capacity.
3Manufacturing precision
If wet coating method is used to apply lithium-containing compounds, then uniform coating is achieved, but the process complexity and energy consumption increase
Solution Approach 1:
The patent extracts the liquid solvent from the coating process, using only dry powder mixing and low-temperature treatment. This eliminates the complex drying and high-temperature calcination steps required in wet coating methods, reducing process complexity while maintaining coating uniformity through simple mechanical mixing and gentle thermal treatment.
Solution Approach 2:
The patent replaces the chemical-wet coating mechanism with a mechanical dry mixing approach followed by low-temperature thermal treatment. This substitution eliminates the need for solvent evaporation and high-temperature calcination, simplifying the process while achieving uniform coating distribution through mechanical mixing.
4Stability of the object's composition
If high-temperature calcination is used to form the coating, then complete reaction and stable coating are achieved, but the ionic conductivity is reduced
Solution Approach 1:
The patent fundamentally changes the temperature parameter from high-temperature calcination (>600°C) to low-temperature treatment (≤500°C, preferably 300-450°C). This parameter change is sufficient to achieve complete reaction and stable coating formation while preventing crystallization, thereby maintaining high ionic conductivity in the amorphous lithium-containing phase.
Solution Approach 2:
The patent uses controlled periodic heating with specific heating rates (5-20°C/min) and holding times (1-10 hours) at low temperature. This periodic thermal treatment allows complete reaction and stable coating formation gradually, avoiding the need for high-temperature rapid processing that would cause crystallization and reduce ionic conductivity.
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 method enhances the cycling performance and discharge capacity of lithium-ion batteries by maintaining high ionic conductivity and stability, outperforming traditional calcinated coatings.
Implementation Method 1
Such all-solid-state secondary lithium-ion batteries should have high ionic conductivity at an interface between an electrode active material and an electrolyte
Implementation Method 2
The present invention relates to a method for making a transition metal oxide coated with an at least partially amorphous lithium-containing coating comprising the step of dry mixing a transition metal oxide with an at least partially amorphous powder comprising lithium
Implementation Method 3
followed by sintering, to create a coated transition metal oxide that improves cycling performance and discharge capacity
Data Source
Figure 1~2
Figure 3~4
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.