Multilayer Surface Electrolyte Interphase for Low-Resistance Batteries
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Solution Overview
Problem
Conventional rechargeable batteries face challenges in achieving optimal stability and performance due to the limitations of the monolithic surface electrolyte interphase (SEI), which often has high ion diffusion resistance and mechanical instability, particularly in advanced energy storage devices like electric vehicles.
Innovation Solution
The introduction of a tailored multilayer or graded surface electrolyte interphase (SEI) with distinct layers or a transition region, comprising inorganic and organic-rich compounds, formed through an in situ electrochemical reaction, to enhance chemical stability, ionic conductivity, and mechanical strength, thereby improving battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a monolithic surface electrolyte interphase (SEI) is used, then the battery structure is simple, but the ion diffusion resistance is high and mechanical stability is poor
Solution Approach 1:
The patent divides the monolithic SEI into multiple distinct layers (first SEI layer, second SEI layer, and optionally third SEI layer), where each layer has different compositions and functions. This segmentation allows optimization of ion diffusion pathways while distributing mechanical stress across multiple interfaces, thereby improving both ionic conductivity and mechanical stability without excessive complexity.
Solution Approach 2:
The patent employs composite SEI structures where different layers are composed of various materials (e.g., inorganic compounds, organic compounds, fluorinated compounds) with complementary properties. This composite approach enables the SEI to simultaneously achieve low ion diffusion resistance through conductive layers and high mechanical stability through protective layers, resolving the contradiction between simplicity and performance.
2Reliability
If a monolithic SEI is used, then the manufacturing process is simple, but the chemical stability is insufficient
Solution Approach 1:
The patent incorporates SEI-forming additives in the electrolyte composition before battery assembly, which pre-form the multi-layer SEI structure during initial charging cycles. This preliminary action eliminates the need for complex post-assembly SEI formation processes, maintaining ease of manufacture while achieving superior chemical stability through the tailored multi-layer structure.
Solution Approach 2:
The patent controls SEI layer formation by adjusting electrolyte composition parameters (additive types and concentrations) and formation cycle parameters (voltage, current, temperature). These parameter changes enable the spontaneous formation of stable multi-layer SEI structures during standard manufacturing processes, improving chemical stability without significantly increasing manufacturing complexity.
3Productivity
If the SEI has high ion diffusion resistance, then the manufacturing is simpler, but the battery performance is reduced
Solution Approach 1:
The patent creates SEI layers with locally optimized properties: the first SEI layer in contact with the negative electrode is designed with high ionic conductivity and appropriate Li concentration to facilitate rapid ion diffusion, while subsequent layers provide mechanical protection and chemical stability. This local quality differentiation improves battery performance without requiring complex external control systems.
Solution Approach 2:
The patent designs the electrolyte composition with specific additives that automatically form the optimized multi-layer SEI structure during initial charging cycles without external intervention. The SEI structure self-adjusts to provide low ion diffusion resistance at the electrode interface while maintaining overall structural integrity, thereby improving productivity without adding manufacturing complexity.
4Reliability
If dendrite growth is not suppressed, then the SEI structure is simpler, but the battery safety is compromised
Solution Approach 1:
The patent designs the multi-layer SEI structure with mechanically robust outer layers that act as protective barriers before dendrites can penetrate through to the separator. This beforehand cushioning approach prevents dendrite-induced short circuits and safety failures, while the layered structure remains achievable through standard electrolyte formulations and formation processes.
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 tailored SEI structure reduces ion diffusion resistance, suppresses dendrite growth, and enhances mechanical stability, leading to improved battery efficiency and safety in energy storage devices.
Implementation Method 1
formed through an in situ electrochemical reaction
Implementation Method 2
reduces ion diffusion resistance
Data Source
AI summary
A battery comprising a separator, a conductive substrate, a negative electrode coupled to the conductive substrate and a surface electrolyte interphase (SEI) disposed between the separator and the negative electrode. The surface electrolyte interphase comprising a first layer coupled to and forming a first interface with the negative electrode, and a second layer coupled to the first layer and forming a second interface with the separator, the first layer being made of a first material and the second layer being made of a second material that is different than the first material.