Alkali Metal Nitrate Coating for Stable Lithium Metal Interfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for applying protective layers to alkali metal or alkali metal alloy surfaces in batteries, such as lithium, face challenges including complexity, high energy consumption, and contamination risks, particularly in dry chemical methods, and the instability of the solid electrolyte interphase (SEI) layer in lithium-sulfur batteries due to polysulfide reactions.
Innovation Solution
A method involving a plasma discharge to activate a gas containing nitrogen compounds, such as nitrous oxide, which is then used to form a protective layer with a high concentration of alkali metal nitrate on the alkali metal or alkali metal alloy surface, reducing the number of processing steps and energy consumption, and enhancing the stability of the SEI layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet chemical methods are used to deposit protective layers, then the protective layer can be formed on the alkali metal surface, but the method is complex and requires multiple processing steps
Solution Approach 1:
The patent extracts and eliminates the intermediate buffer layer step from the conventional two-step process. By using plasma-enhanced chemical vapor deposition, the protective layer can be deposited directly on the alkali metal surface without requiring a separate buffer layer formation step, thereby simplifying the overall process while maintaining protective functionality.
Solution Approach 2:
The patent combines the buffer layer formation and protective layer deposition into a single plasma treatment step. By introducing specific precursor gases during plasma treatment, both the buffering function and protective function are achieved simultaneously in one processing step rather than requiring separate sequential steps.
2Device complexity
If dry chemical methods are used to form protective layers, then the number of processing steps is reduced, but the energy consumption increases
Solution Approach 1:
The patent uses plasma enhancement to enable protective layer formation at lower temperatures compared to conventional dry chemical methods. By utilizing plasma activation, the reaction can proceed under milder conditions, reducing the energy input required while still achieving effective protective layer deposition in a single step.
3Reliability
If conventional protective layers are used in lithium-sulfur batteries, then the SEI layer is formed, but it becomes unstable due to polysulfide reactions
Solution Approach 1:
The patent introduces a plasma-treated protective layer as an intermediary between the lithium metal and the polysulfides in the electrolyte. This protective layer acts as a barrier that prevents direct contact and harmful reactions between polysulfides and the SEI layer, thereby maintaining SEI stability. The plasma treatment modifies the surface properties to create this protective intermediary function.
Solution Approach 2:
The patent creates a composite protective structure through plasma treatment that combines multiple functional components. The plasma process deposits a composite layer with both buffering capacity and protective properties, forming a multi-functional composite material that simultaneously provides SEI stability and resistance to polysulfide attack.
4Reliability
If the protective layer is made thicker to improve protection, then the corrosion resistance increases, but the interface resistance and overall cell resistance increase
Solution Approach 1:
The patent uses plasma treatment parameters (power, gas flow rate, treatment time) to precisely control the thickness and composition of the protective layer. By optimizing these parameters, the protective layer achieves the minimum necessary thickness for effective corrosion protection while maintaining low resistance, avoiding the need for excessive thickness that would increase interface resistance.
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 results in a protective layer with improved stability and efficiency, reducing interface resistance and overall cell resistance, and achieving high Coulombic efficiency in battery cells, especially in lithium-sulfur batteries, with reduced risk of corrosion and polysulfide shuttling.
Implementation Method 1
A method involving a plasma discharge to activate a gas containing nitrogen compounds
Implementation Method 2
which is then used to form a protective layer with a high concentration of alkali metal nitrate on the alkali metal or alkali metal alloy surface
Data Source
AI summary
A method is disclosed for applying a protective layer on at least part of an exposed alkali metal or alkali metal alloy substrate. The method includes activating a gas using a plasma discharge to obtain an activated gas and contacting the exposed surface with the activated gas. A protective layer is formed on at least part of the exposed surface. The gas has a nitrogen-comprising compound such that the protective layer includes at least 60 mol % of a corresponding alkali metal nitrate. The present disclosure is further related to an article including a substrate having a surface including an alkali metal or alkali metal alloy and a protective layer arranged on at least part of the alkali metal or alkali metal alloy surface of the substrate. The protective layer is conductive to ions of the corresponding alkali metal and has at least 60 mol % of a corresponding alkali metal nitrate.