Non-aqueous electrolyte with cyclic diester and sulfinyl compound
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Solution Overview
Problem
Conventional non-aqueous electrolytes in lithium secondary batteries suffer from decomposition and structural collapse of the anode, leading to reduced lifespan and high-temperature instability due to the lack of effective solid electrolyte interface (SEI) film stability.
Innovation Solution
Incorporating a cyclic diester compound and a sulfinyl group-containing compound as electrolyte additives to form a dual-layer SEI film with enhanced thermal and physical stability, optimizing the SEI film's rigidity and stability through controlled reduction potentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte interface (SEI) film is formed on the anode surface via electrolyte solvent reduction, then the anode is protected from electrolyte decomposition, but the SEI film is not thermally stable and decomposes at high temperatures, leading to gas generation and battery swelling
Solution Approach 1:
The patent changes the chemical composition parameters of the SEI film by introducing compounds containing specific functional groups (carboxyl, hydroxyl, amine, or phosphine groups). These functional groups modify the reduction potential and decomposition characteristics of the SEI film, enabling it to maintain stability at high temperatures while still providing protection at lower temperatures.
Solution Approach 2:
The patent creates a composite SEI film structure by combining conventional electrolyte additives with compounds containing specific functional groups. This composite approach integrates the protective function of traditional SEI films with the thermal stability provided by functional groups that resist decomposition at elevated temperatures, preventing gas generation and battery swelling.
2Duration of action of stationary object
If conventional electrolyte additives are used to form SEI film, then the anode is protected during charge/discharge cycles, but the SEI film decomposes easily under high temperature conditions, degrading battery high-temperature stability
Solution Approach 1:
The patent modifies the chemical parameters of the SEI film-forming compounds by selecting substances with specific functional groups (carboxyl, hydroxyl, amine, or phosphine groups) and controlling their content within 0.01-5 wt%. This parameter optimization ensures the SEI film maintains its protective function during cycling while achieving the required thermal stability for high-temperature operation.
Solution Approach 2:
The functional group-containing compounds act as intermediaries between the anode and the electrolyte. These compounds form a SEI film that mediates the interaction between the anode and electrolyte, providing both the protective function needed for cycle stability and the thermal resistance required for high-temperature stability, thereby resolving the contradiction between these two requirements.
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 cyclic diester and sulfinyl group-containing compounds significantly improves battery lifespan and high-temperature stability by forming a robust SEI film, maintaining capacity and preventing swelling under high-temperature conditions.
Implementation Method 1
the SEI film being formed by electrical reduction of a cyclic diester compound and a sulfinyl group-containing compound
Implementation Method 2
an electrolyte comprising an electrolyte solvent and an electrolyte salt
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 cyclic diester 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.