Non-aqueous Electrolyte with Lactam and Sulfinyl Additives for SEI Stability
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Solution Overview
Problem
Conventional secondary battery electrolytes suffer from decomposition and structural collapse during charge/discharge cycles, leading to reduced battery lifespan and instability at high temperatures, as the solid electrolyte interface (SEI) film formed is physically weak and thermally unstable.
Innovation Solution
A non-aqueous electrolyte comprising a lactam-based compound and a sulfinyl group-containing compound is used to form a stable SEI film on the anode, optimizing both physical and thermal stability by combining compounds with different stability characteristics, resulting in a robust and thermally stable SEI film with enhanced lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrolyte solvent is used, then the battery can operate, but the electrolyte is decomposed on the electrode surface and co-intercalated into the anode, causing structural collapse and degradation of battery stability
Solution Approach 1:
The patent applies preliminary action by introducing a film-forming electrolyte additive that forms a protective SEI film on the anode surface before the electrolyte solvent can co-intercalate and cause damage. This preliminary protective layer prevents the harmful co-intercalation of electrolyte components into the anode structure during subsequent charge/discharge cycles, thereby maintaining battery stability.
Solution Approach 2:
The patent uses a film-forming electrolyte additive as an intermediary substance that mediates between the electrolyte solvent and the anode. This additive forms a stable interfacial layer that allows lithium ion transport while blocking the harmful co-intercalation of electrolyte components, thus protecting the anode structure without preventing normal battery operation.
2Reliability
If a SEI film is formed on the anode, then electrolyte decomposition is reduced, but the SEI film is not thermally stable and breaks down at high temperatures, causing gas generation and increased internal pressure
Solution Approach 1:
The patent applies composite materials by combining multiple electrolyte additives with different functional characteristics to form a composite SEI film. This composite film integrates the benefits of each additive: one component provides low-temperature stability and lithium ion conductivity, while another component provides high-temperature stability. The synergistic combination creates a multi-layered protective film that maintains integrity across a wide temperature range, preventing both electrolyte decomposition and thermal breakdown.
3Reliability
If vinylene carbonate is used as an electrolyte additive, then a SEI film is formed on the anode, but the SEI film is decomposed easily under high temperature conditions, resulting in degradation of high temperature stability
Solution Approach 1:
The patent merges vinylene carbonate with another electrolyte additive that has complementary high-temperature stability properties. This combination creates a synergistic effect where the vinylene carbonate forms the base SEI film structure, while the co-additive reinforces the film's thermal stability. The merged system produces a SEI film that retains the good low-temperature performance of vinylene carbonate while gaining enhanced high-temperature resistance from the combined additives.
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 combination of lactam-based and sulfinyl group-containing compounds significantly improves battery lifespan and high-temperature stability, minimizing capacity drop during cycles and maintaining battery performance under elevated temperatures.
Implementation Method 1
the SEI film being formed by electrical reduction of a lactam-based compound and a sulfinyl group-containing compound
Data Source
AI summary
Disclosed is an electrolyte for a secondary battery comprising an electrolyte salt and an electrolyte solvent, the electrolyte further comprising both a lactam-based compound and a sulfinyl group-containing compound. Also, disclosed is an electrode having a solid electrolyte interface (SEI) film partially or totally formed on a surface thereof, the SEI film being formed by electrical reduction of the above compounds. Further, a secondary battery comprising the electrolyte and/or the electrode is disclosed.