Cyclodextrin Additives for Silicon Anode SEI Stability
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Solution Overview
Problem
Conventional lithium-ion batteries with silicon-based anodes face challenges such as large volume changes, unstable solid-electrolyte interphase (SEI) formation, and electrolyte decomposition, leading to reduced cycle life and energy density, especially when paired with high-voltage cathodes like Ni-rich NCM or LCO.
Innovation Solution
Incorporation of cyclodextrin-based compounds as additives in the electrolyte or electrode compositions to form stable, electronically insulating but ionically conductive SEI layers on silicon anodes and high-voltage cathodes, mitigating volume expansion, electrolyte decomposition, and transition metal ion dissolution, thereby enhancing cycle life and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anodes are used to increase energy density, then battery capacity is improved, but volume expansion and SEI instability occur reducing cycle life
Solution Approach 1:
Cyclodextrin-based compounds serve as intermediary substances that mediate between the silicon anode and electrolyte. These compounds form stable SEI layers that prevent direct harmful interactions while allowing lithium ion transport, thus protecting the silicon anode from volume expansion damage and electrolyte decomposition without reducing battery capacity
Solution Approach 2:
The invention changes the chemical composition parameters of the SEI layer by introducing cyclodextrin-based compounds. This alters the physical and chemical properties of the interface, creating a more stable SEI with appropriate ion conductivity and electronic insulation, thereby improving cycle life while maintaining high capacity
2Quantity of substance
If high-voltage cathodes are used to increase energy density, then battery capacity is improved, but electrolyte decomposition and transition metal ion dissolution occur
Solution Approach 1:
Cyclodextrin-based compounds act as protective intermediaries between the high-voltage cathode and electrolyte. They form stable interfacial layers that prevent direct contact and harmful reactions, suppressing electrolyte decomposition and transition metal ion dissolution while maintaining high voltage operation and battery capacity
3Reliability
If conventional electrolyte additives are used to stabilize SEI, then cycle life is improved, but energy density is reduced due to complex formulations
Solution Approach 1:
The invention changes the chemical structure parameters of the electrolyte additive by using cyclodextrin-based compounds with specific molecular structures. These structures provide both SEI stabilization and high voltage compatibility, achieving improved cycle life and energy density simultaneously through optimized molecular design rather than complex formulations
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 use of cyclodextrin-based compounds improves the stability of the SEI layer on silicon anodes and cathodes, reducing impedance, preventing electrolyte decomposition, and increasing the oxidation stability of electrolytes, resulting in enhanced cycle performance, energy density, and safety of lithium-ion batteries.
Implementation Method 1
Incorporation of cyclodextrin-based compounds as additives in the electrolyte or electrode compositions to form stable, electronically insulating but ionically conductive SEI layers on silicon anodes and high-voltage cathodes
Implementation Method 2
mitigating volume expansion, electrolyte decomposition, and transition metal ion dissolution, thereby enhancing cycle life and energy density
Implementation Method 3
increasing the oxidation stability of electrolytes, resulting in enhanced cycle performance, energy density, and safety of lithium-ion batteries
Data Source
AI summary
Additives for energy storage devices comprising cyclodextrin-based compounds and their derivatives are disclosed. The energy storage device comprises a first electrode and a second electrode, where at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, and an electrolyte composition. Cyclodextrin-based compounds may serve as additives to the first electrode, the second electrode, and/or the electrolyte.