Siloxane Sulfonate Electrolyte for Lithium Battery SEI Stability
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Solution Overview
Problem
Lithium secondary batteries using non-aqueous electrolyte solutions with siloxane compounds experience capacity degradation and swelling issues over time, particularly under high temperature conditions due to the instability of the SEI film.
Innovation Solution
A non-aqueous electrolyte solution for lithium secondary batteries is developed, incorporating a siloxane compound like 1,3-divinyltetramethyldisiloxane and a sulfonate compound such as 1,3-dioxolane-2-onylmethyl allyl sulfonate, which forms a more stable polymer-type SEI film on the anode surface, enhancing initial stability and reducing capacity degradation and swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a siloxane compound is added to improve life cycle and low temperature characteristics, then the battery's life cycle and low temperature performance are improved, but capacity degradation occurs during long-time use
Solution Approach 1:
The patent combines siloxane compound (for life cycle and low temperature improvement) with cyclic carboxylate compound and chain carboxylate compound (for capacity retention) to form a composite electrolyte system. This composite approach allows the electrolyte to simultaneously achieve improved life cycle, maintained capacity, and low temperature performance through synergistic effects of multiple additives.
2Stability of the object's composition
If a siloxane compound is added to enhance SEI film stability, then initial stability is improved, but the SEI film becomes thermally unstable under high temperature conditions
Solution Approach 1:
The patent modifies the SEI film composition by introducing cyclic carboxylate compound and chain carboxylate compound alongside siloxane compound. These additives change the chemical composition parameters of the SEI film, creating a more thermally stable structure that maintains integrity under high temperature conditions while preserving initial stability benefits.
Solution Approach 2:
The electrolyte uses a composite additive system combining siloxane compound with cyclic carboxylate compound and chain carboxylate compound. This composite approach creates a SEI film with balanced properties: initial stability from siloxane, and thermal stability from carboxylate compounds, resolving the thermal instability issue.
3Adaptability or versatility
If a siloxane compound is used to improve low temperature characteristics, then low temperature performance is enhanced, but battery swelling occurs over time
Solution Approach 1:
The patent employs a composite electrolyte formulation combining siloxane compound (for low temperature performance) with cyclic carboxylate compound and chain carboxylate compound (for swelling prevention). This composite system maintains low temperature adaptability while the carboxylate additives suppress battery swelling through enhanced SEI film stability.
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 solution effectively addresses capacity degradation and swelling problems by forming a stable SEI film, improving the battery's life cycle and performance, especially under high temperature conditions.
Implementation Method 1
the sulfonate compound such as 1,3-dioxolane-2-onylmethyl allyl sulfonate, which forms a more stable polymer-type SEI film on the anode surface
Implementation Method 2
Lithium ions coming out from a cathode active material such as lithium metal oxide during an initial charging process of a lithium secondary battery are moved to an anode active material such as graphite and then intercalated between layers of the anode active material. At this time, due to the strong reactivity of lithium, electrolyte reacts with carbon of the anode active material on the surface of the anode active material such as graphite, thereby generating compounds such as Li2CO3, Li2O and LiOH.
Implementation Method 3
Lithium ions coming out from a cathode active material such as lithium metal oxide during an initial charging process of a lithium secondary battery are moved to an anode active material such as graphite and then intercalated between layers of the anode active material
Implementation Method 4
The SEI film plays a role of ion tunnel, which allows only lithium ions to pass.
Data Source
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AI summary
A non-aqueous electrolyte solution for a lithium secondary battery includes a lithium salt and an organic solvent. The non-aqueous electrolyte solution further includes a specific siloxane compound and a sulfonate compound. This non-aqueous electrolyte solution solves the capacity degradation phenomenon, which appears in a lithium secondary battery using a non-aqueous electrolyte solution containing only a specific siloxane compound when the lithium secondary battery is used for a long time, so this non-aqueous electrolyte solution is especially useful for high-capacity batteries.