Anhydride Electrolyte Additives for Stable Silicon Battery Interfaces
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Solution Overview
Problem
Lithium-ion batteries with silicon-based anodes and high-voltage nickel-rich cathodes face challenges such as unstable solid electrolyte interphase layers, oxidative instability, and poor cycling life due to volumetric expansion and transition metal ion dissolution, limiting their energy density and safety.
Innovation Solution
The development of anhydride-based electrolyte additives that form stable, electronically insulating but ionically conducting solid electrolyte interphase layers on silicon anodes and cathode electrolyte interphase films, enhancing mechanical strength, thermal stability, and reducing flammability to improve the electrochemical performance and safety of silicon-based lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based anodes are used to increase energy density, then capacity is improved, but volumetric expansion during lithiation causes disintegration and reduces cycling life
Solution Approach 1:
The anhydride additive performs preliminary action by forming a stable SEI layer on the silicon anode surface before the electrolyte can decompose. This pre-formed protective layer prevents subsequent electrolyte reduction and maintains interface stability during silicon expansion and contraction cycles.
Solution Approach 2:
The anhydride-derived SEI layer acts as an intermediary between the silicon anode and the liquid electrolyte. This intermediate layer mechanically accommodates silicon volumetric changes while chemically preventing direct contact between the electrolyte and silicon surface, thereby preventing electrolyte decomposition and maintaining cycling stability.
2Quantity of substance
If conventional electrolytes are used with high-voltage cathodes, then energy density is improved, but oxidative instability occurs beyond 4.5 V leading to accelerated decay
Solution Approach 1:
The anhydride additive performs preliminary oxidation at the cathode interface before the bulk electrolyte can undergo oxidative decomposition. By forming a CEI film on the high-voltage cathode surface first, it prevents subsequent electrolyte oxidation even at potentials beyond 4.5 V.
Solution Approach 2:
The anhydride additive changes the electrochemical stability window parameters of the electrolyte system. By introducing this additive, the oxidation potential threshold is effectively extended beyond 4.5 V, allowing high-voltage cathodes to operate stably at elevated potentials without electrolyte decomposition.
3Quantity of substance
If silicon anodes are used to achieve high capacity, then energy density is improved, but unstable SEI layer leads to endless electrolyte exposure and irreversible capacity loss
Solution Approach 1:
The anhydride additive forms a stable SEI layer during initial cycles before the electrolyte can repeatedly decompose. This preliminary SEI formation prevents subsequent electrolyte reduction reactions that would otherwise cause continuous irreversible capacity loss.
Solution Approach 2:
The anhydride-derived SEI layer serves as a stable intermediary that prevents direct electrolyte contact with the silicon anode surface. This intermediate layer eliminates the endless cycle of electrolyte decomposition and reformation, thereby preventing irreversible capacity loss while maintaining silicon's high capacity.
4Quantity of substance
If transition metal ions dissolve into electrolyte from NCM/NCA cathodes, then capacity is improved, but stability deteriorates due to surface layer exfoliation and continuous decomposition
Solution Approach 1:
The anhydride-derived CEI film acts as an intermediary protective layer between the NCM/NCA cathode and the liquid electrolyte. This intermediate film prevents transition metal ion dissolution into the electrolyte and stops continuous electrolyte decomposition, thereby stabilizing the cathode surface layer while maintaining high capacity.
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 anhydride additives improves the cycle life, energy density, and safety of silicon-based lithium-ion batteries by stabilizing the electrolyte interface, reducing electrolyte decomposition, and enhancing thermal stability, leading to improved electrochemical performance and reduced risk of mechanical and electrical failure.
Implementation Method 1
anhydride-based electrolyte additives that form stable, electronically insulating but ionically conducting solid electrolyte interphase layers on silicon anodes
Implementation Method 2
formative of a stable cathode electrolyte interphase film on high voltage cathodes
Implementation Method 3
ionically conducting solid electrolyte interphase layers
Data Source
AI summary
Electrolytes and electrolyte additives for energy storage devices including an anhydride compound are provided. The energy storage device includes 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, an electrolyte, and at least one electrolyte additive which is an anhydride compound.