Linear Carbonate Electrolytes 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 poor cycling stability due to volumetric expansion, unstable solid electrolyte interphase layers, and oxidative instability of conventional electrolytes, leading to reduced energy density and safety concerns.
Innovation Solution
The development of novel electrolyte additives that form stable, electronically insulating but ionically conducting solid electrolyte interphase (SEI) layers on silicon anodes and cathode electrolyte interphase (CEI) films, using linear carbonate compounds to enhance mechanical strength, prevent electrolyte decomposition, and improve thermal stability, thereby stabilizing the electrochemical environment and reducing flammability.
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 leads to disintegration and reduced cycling stability
Solution Approach 1:
The patent employs flexible polymer coatings and thin film structures that can accommodate the volumetric expansion of silicon during lithiation. These flexible layers prevent mechanical disintegration while maintaining electrical contact, allowing silicon to achieve its high capacity without suffering from volume expansion-induced failure.
Solution Approach 2:
The patent utilizes composite material structures combining silicon with other materials (such as carbon matrices or metal oxides) to create a composite anode. This composite approach provides structural support to withstand volume changes while maintaining the high capacity benefits of silicon, thereby improving both energy density and cycling stability.
2Productivity
If conventional non-aqueous electrolytes are used, then ionic conductivity is achieved, but oxidative instability occurs at voltages beyond 4.5 V leading to accelerated decay
Solution Approach 1:
The patent modifies the chemical composition and physical parameters of the electrolyte by introducing novel additives and adjusting solvent ratios. These parameter changes increase the oxidative stability window of the electrolyte to accommodate high-voltage cathodes while preserving adequate ionic conductivity for battery operation.
3Quantity of substance
If high-voltage nickel-rich cathodes are used to increase energy density, then capacity is improved, but surface layer exfoliation and electrolyte decomposition reduce cycling stability
Solution Approach 1:
The patent introduces surface coating layers and electrolyte additives that act as intermediaries between the nickel-rich cathode and the electrolyte. These intermediary layers prevent direct contact and harmful reactions, reducing surface layer exfoliation and electrolyte decomposition while allowing the high-capacity cathode to function stably over many cycles.
4Quantity of substance
If silicon anodes with high capacity are used, then energy density is improved, but unsafe conditions arise due to unstable SEI layers and continuous electrolyte decomposition
Solution Approach 1:
The patent employs preliminary surface treatments and pre-formed stable SEI layers on silicon anodes before battery operation. This preliminary action creates a protective barrier that prevents continuous electrolyte decomposition and unstable SEI formation during cycling, thereby eliminating safety hazards while preserving the high energy density benefits of silicon.
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 these additives improves the cycling stability and safety of silicon-based lithium-ion batteries by forming robust SEI and CEI layers, reducing capacity fade, and enhancing thermal stability, leading to increased cycle life and safety.
Implementation Method 1
form stable, electronically insulating but ionically conducting solid electrolyte interphase (SEI) layers on silicon anodes
Implementation Method 2
prevent electrolyte decomposition
Implementation Method 3
form stable, electronically insulating but ionically conducting solid electrolyte interphase (SEI) layers on silicon anodes and cathode electrolyte interphase (CEI) films
Implementation Method 4
protect transition metal ion dissolution from NCM cathode
Implementation Method 5
the large volumetric expansion (>300%) during the Li alloying/dealloying processes can lead to disintegration of the active material
Implementation Method 6
enhance mechanical strength
Implementation Method 7
enhancing thermal stability, leading to increased cycle life and safety
Implementation Method 8
reducing flammability
Data Source
AI summary
Electrolytes and electrolyte additives for energy storage devices comprising linear carbonate compounds.