Non-Aqueous Electrolyte Composition for Stable Metal-Anode SEI
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Solution Overview
Problem
Current electrolyte compositions for metal ion batteries suffer from low coulombic efficiency (CE) due to the instability and non-uniformity of the solid electrolyte interface (SEI) formed on metal anodes, leading to metal dendrite growth and reduced cycle life.
Innovation Solution
The development of electrolyte compositions that include specific solvents, electrolyte salts, and non-polar additives, such as cyclic sulfones, fluorinated sulfonamides, and aromatic hydrocarbons, which enhance the formation of uniform, fast metal ion conductors and self-healing SEI layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte compositions are used with metal anodes, then the battery can operate, but the solid electrolyte interface (SEI) formed is unstable and non-uniform, leading to low coulombic efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by introducing specific additives (fluorinated cyclic carbonate, cyclic carboxylic acid ester, and cyclic sulfite) with controlled weight ratios (0.1-5% each) to modify the SEI formation process, transforming the unstable conventional SEI into a stable composite SEI structure that enables high coulombic efficiency
Solution Approach 2:
The patent creates a composite SEI layer through the synergistic interaction of multiple electrolyte components. The fluorinated cyclic carbonate, cyclic carboxylic acid ester, and cyclic sulfite work together to form a multi-component SEI structure that combines the benefits of each component, achieving both stability and high ion conductivity
2Quantity of substance
If metal anodes with low negative electrochemical potential are employed to increase energy density, then energy density improves, but reactivity with the electrolyte increases causing SEI formation and metal dendrite growth
Solution Approach 1:
The patent introduces specific electrolyte additives as intermediary substances that mediate between the highly reactive metal anode and the bulk electrolyte. These additives preferentially react with the metal surface to form a protective SEI layer that acts as an intermediary barrier, preventing direct harmful reactions between the metal and conventional electrolyte components while maintaining ion transport
3Duration of action of stationary object
If the SEI is regenerated repeatedly during charge and discharge cycles, then metal plating and stripping continues, but additional electrolyte is decomposed and coulombic efficiency is significantly reduced
Solution Approach 1:
The patent applies preliminary action by having the new electrolyte additives react with the metal anode surface during initial cycles to form a stable, low-resistance SEI layer before conventional SEI formation occurs. This pre-formed stable SEI prevents subsequent repeated decomposition and regeneration cycles, eliminating the progressive energy loss that would otherwise occur during normal operation
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
These electrolyte compositions achieve a coulombic efficiency of at least 90% for plating and stripping of alkali metals, alkaline earth metals, zinc, and aluminum, significantly improving the performance and cycle life of metal ion batteries.
Implementation Method 1
at least one solvent which solubilizes the at least one electrolyte salt; wherein the at least one solvent which solubilizes the at least one electrolyte salt is selected from the group consisting of cyclic sulfones, cyclic sultones, cyclic ethers, partially fluorinated sulfonamides, fluorinated solvents, and glymes
Implementation Method 2
The reduction of the electrolyte on the surface of the metal anode results in the formation of a solid electrolyte interface (SEI)
Data Source
AI summary
Electrolyte compositions for secondary batteries having a metal anode are provided. The compositions include an electrolyte salt of an alkali metal, an alkaline earth metal, zinc, or aluminum; at least one solvent which solubilizes the electrolyte salt; and up to 25 wt. % of a selected non-polar additive. The solvent is selected from cyclic sulfones, cyclic sultones, cyclic ethers, partially fluorinated sulfonamides, fluorinated solvents and glymes. The nonpolar additive is selected from aromatic hydrocarbons, partially fluorinated aromatic hydrocarbons, fluorinated monoethers, partly fluorinated polyethers, fluorinated phosphate esters and fluorinated linear sulfones. Multiple combinations of metal salts, solvents and nonpolar additives having a coulombic efficiency of with respect to plating and stripping of the metal of at least 90% are provided.