Dual Electrolyte SEI Formation for Stable Li-Ion Cell Filling
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Solution Overview
Problem
Evaporation of the liquid electrolyte during the filling process of lithium-ion battery cells alters the electrolyte composition, affecting the formation of the solid electrolyte interphase (SEI) on battery cell electrodes, leading to challenges such as transition metal dissolution, gas generation, and capacity decay.
Innovation Solution
The implementation of a dual solid electrolyte interphase layer formed by a first electrolyte with a salt concentration greater than or equal to 1 M and a second electrolyte different from the first, which reduces electrolyte evaporation and enhances cathode and anode interface stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrolyte is used in the battery cell, then the device complexity is low, but the solid electrolyte interphase formation is affected due to electrolyte evaporation during filling
Solution Approach 1:
The patent divides the electrolyte system into two distinct electrolytes: a first electrolyte with high salt concentration (≥1 M) that forms the initial solid electrolyte interphase, and a second electrolyte that forms a protective layer to prevent evaporation. This segmentation allows each electrolyte to perform its specific function optimally without interfering with the other.
Solution Approach 2:
The first electrolyte is introduced first to form the solid electrolyte interphase on the electrode surface before the second electrolyte is added. This preliminary action ensures that the SEI layer is established under controlled conditions with high salt concentration, which is critical for proper interphase formation.
2Productivity
If electrolyte evaporation is not controlled during filling, then the filling process is simple, but the electrolyte composition changes and affects battery performance
Solution Approach 1:
The patent converts the harmful effect of evaporation into a beneficial outcome by using the second electrolyte to form a protective layer that prevents further evaporation. The controlled evaporation of the first electrolyte during filling actually helps establish the desired solid electrolyte interphase, while the second electrolyte then locks in the composition.
Solution Approach 2:
The battery cell contains a composite electrolyte system with two different electrolytes having distinct compositions and functions. The first electrolyte (high salt concentration) and second electrolyte (protective) work together as a composite system to achieve both proper SEI formation and evaporation prevention.
3Reliability
If a first electrolyte with high salt concentration is used to form solid electrolyte interphase, then the interphase formation is improved, but electrolyte evaporation increases
Solution Approach 1:
The electrolyte system is segmented into two functional components: the first electrolyte dedicated to SEI formation with high salt concentration, and the second electrolyte dedicated to evaporation prevention. This segmentation allows the high salt concentration electrolyte to perform its interphase formation function without the negative consequence of excessive evaporation.
Solution Approach 2:
The second electrolyte acts as an intermediary protective layer between the first electrolyte and the environment. It mediates the evaporation process by forming a barrier that prevents the first electrolyte from evaporating, while still allowing the first electrolyte to maintain its high salt concentration for effective SEI formation.
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
This approach improves battery cell performance by reducing electrolyte evaporation, stabilizing the cathode and anode interfaces, and maintaining thermal stability during the electrochemical filling process.
Implementation Method 1
a first solid electrolyte interphase on the electrode. The first solid electrolyte interphase can be formed from a first electrolyte
Implementation Method 2
a second solid electrolyte interphase on the first solid electrolyte interphase. The second electrolyte can form a second solid electrolyte interphase on the first solid electrolyte interphase
Data Source
AI summary
Provided herein is an apparatus. The apparatus can include a battery cell. The battery cell can include an electrode. The apparatus can include a first solid electrolyte interphase on the electrode. The first solid electrolyte interphase can be formed from a first electrolyte having a salt concentration greater than or equal to 1 M. The apparatus can include a second solid electrolyte interphase on the electrode. The second solid electrolyte interphase can be formed from a second electrolyte different from the first electrolyte.