Silylated Cellulose Coating for Magnesium Anode Passivation
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Solution Overview
Problem
Lithium-ion batteries face challenges due to high costs and limited availability of lithium, necessitating alternatives like aluminum, zinc, and magnesium for improved storage capacity in electric mobility applications, but these metals require effective protective coatings to prevent passivation and corrosion in electrochemical cells.
Innovation Solution
A protective layer composed of silylated cellulose, optionally with ion conductive additives solvated in a solvent, is applied to the surface of electrically conductive materials like magnesium, zinc, and aluminum to prevent passivation, ensure ion transport, and allow the use of chloride-free electrolytes, thereby enhancing the stability and cycle life of electrochemical cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnesium-based materials are used as anodes to replace lithium, then storage capacity per unit volume is improved, but passivation and corrosion occur reducing reliability
Solution Approach 1:
The patent applies composite materials by combining silylated cellulose with ion-conductive additives (such as lithium salts or magnesium salts) to create a protective layer that integrates multiple functions: physical protection against passivation, ionic conductivity for electrochemical performance, and chemical stability. This composite structure resolves the contradiction by maintaining the high storage capacity of magnesium while adding protective functionality that prevents corrosion and passivation.
Solution Approach 2:
The patent utilizes parameter changes by controlling the degree of silylation of cellulose (using different molar ratios of silylating agents like TMSCl or TMSBr), adjusting the composition and concentration of ion-conductive additives, and optimizing solvent selection to achieve the desired balance between protective properties and ionic conductivity. These parameter adjustments allow tuning the protective layer to prevent passivation while maintaining electrochemical performance.
2Reliability
If a protective layer is applied to prevent passivation, then reliability is improved, but ion transport may be hindered reducing electrochemical performance
Solution Approach 1:
The patent employs porous materials by incorporating ion-conductive additives that create ion transport pathways within the silylated cellulose matrix. The porous or semi-porous structure formed by the composite allows ions to penetrate and transport through the protective layer, resolving the contradiction between providing passivation protection and maintaining ion transport efficiency for electrochemical performance.
Solution Approach 2:
The patent uses ion-conductive additives as intermediaries that facilitate ion transport through the protective layer. These additives act as mediators between the magnesium anode and the electrolyte, enabling ions to pass through the protective silylated cellulose layer without direct contact between the metal and corrosive electrolyte, thus maintaining both protection and ionic conductivity.
3Object-affected harmful factors
If conventional coatings are used on magnesium anodes, then corrosion resistance is improved, but chloride-containing electrolytes cause ongoing degradation
Solution Approach 1:
The patent applies the inert atmosphere principle by using silylated cellulose, which creates a chemically inert and stable protective environment around the magnesium anode. This protective layer is compatible with chloride-free electrolytes, preventing the harmful interactions that occur with conventional coatings and chloride-containing electrolytes. The silylated structure provides chemical stability and inertness that resolves the contradiction between corrosion resistance and electrolyte compatibility.
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 silylated cellulose protective layer effectively prevents passivation, improves metal deposition homogeneity, and allows the use of chloride-free electrolytes, leading to stable performance and extended cycle life of magnesium-based electrochemical cells.
Implementation Method 1
solvent which solvates the at least one ion conductive additive which is present in the protective layer
Data Source
AI summary
The present invention provides a magnesium anode and an electrochemical cell comprising the anode.