Carbonate-Containing Silane for Stable Li-Ion Electrolytes
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Solution Overview
Problem
Lithium ion secondary batteries using nonaqueous electrolyte solutions face safety risks due to the instability of cyclic carbonate-modified siloxane compounds when exposed to fluorine-containing lithium salts, leading to potential ignition and vapor pressure increases.
Innovation Solution
A carbonate-containing silane compound with a characteristic structure where at least two silicon atoms are linked by a carbon chain, which is chemically stable and can be used as an additive in electrolyte solutions, reducing the risk of ignition and improving safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cyclic carbonate-modified siloxane is added to nonaqueous electrolyte solution, then discharge characteristics at low temperature and high outputs are improved, but chemical stability deteriorates due to decomposition by fluorine-containing lithium salts
Solution Approach 1:
The invention changes the chemical structure parameters of the silane compound by replacing siloxane bonds (Si-O-Si) with silicon-carbon-silicon linked structures. This structural parameter change maintains the beneficial discharge characteristics while improving chemical stability against fluorine-containing lithium salts, as the new structure resists decomposition by these salts.
Solution Approach 2:
The invention creates a composite molecular structure combining carbonate groups with silicon-carbon-silicon linked frameworks. This composite structure integrates the surface activity and low-temperature performance enhancement from the carbonate-modified silane with the chemical stability of the carbon-linked silicon backbone, resolving the contradiction between reactivity and stability.
2Object-affected harmful factors
If cyclic carbonate-modified siloxane is used to improve wetting and discharge characteristics, then flame retardancy and low vapor pressure are achieved, but safety deteriorates due to increased ignition risk from decomposition
Solution Approach 1:
The invention changes the molecular structure from siloxane-based to silicon-carbon-silicon linked structure, which fundamentally alters the decomposition behavior. This structural change maintains flame retardancy and low vapor pressure while eliminating the decomposition pathway that leads to safety hazards, thus improving reliability without sacrificing fire safety properties.
3Strength
If siloxane bonds are severed by fluorine atoms, then chemical reactivity increases for surface treatment, but vapor pressure rises and ignition risk increases
Solution Approach 1:
The invention extracts the problematic siloxane bond (Si-O-Si) that is susceptible to fluorine attack and replaces it with a fluorine-resistant silicon-carbon-silicon linked structure. This extraction of the vulnerable component eliminates the decomposition reaction that generates harmful vapor and ignition risk, while preserving the surface activity needed for effective electrolyte performance.
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 carbonate-containing silane compound enhances the chemical stability and safety of lithium ion secondary batteries by preventing decomposition and reducing harmful gas release during burning, thus addressing the safety concerns in rigorous environments.
Implementation Method 1
the carbonate-containing silane compound having a characteristic structure that at least two silicon atoms are linked by a carbon chain is useful as an intermediate of a silane coupling agent and also chemically stable in electrolyte solutions of lithium ion secondary batteries
Implementation Method 2
a method for preparing the carbonate-containing silane compound, comprising the step of effecting condensation reaction of a silyl alcohol compound having the general formula (2) with a halogenated formate having the general formula (3) in the presence of a base
Data Source
AI summary
Provided is a carbonate-containing silane compound having a characteristic structure that at least two silicon atoms are linked by a carbon chain. The silane compound is chemically stable. When used as an additive to a nonaqueous electrolyte solution, the silane compound does not jeopardize the safety of lithium ion secondary batteries.