Ether Electrolyte Additives for Stable Si-Based Li-Ion Interfaces
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Solution Overview
Problem
Lithium-ion batteries with silicon-based anodes and high-voltage nickel-rich cathodes face challenges in long-term cycling stability due to volumetric expansion, unstable solid electrolyte interphase (SEI) layers, and oxidative instability of conventional electrolytes, leading to reduced energy density and safety concerns.
Innovation Solution
The development of ether-based electrolyte additives that form stable, electronically insulating but ionically conducting SEI layers on silicon anodes and cathode electrolyte interphase (CEI) films, enhancing mechanical strength, thermal stability, and reducing flammability, thereby improving the electrochemical performance and safety of silicon anode-based Li-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 leads to disintegration and reduced cycling stability
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable solid electrolyte interphase (SEI) layer on the silicon anode surface before actual battery cycling begins. This is achieved through electrolyte additives that react during initial cycles to create a protective interface layer that prevents subsequent electrolyte decomposition and maintains structural integrity during silicon expansion and contraction
Solution Approach 2:
The patent uses electrolyte additives as intermediary substances that mediate between the silicon anode and the bulk electrolyte. These additives form interfacial layers that act as protective intermediaries, preventing direct contact between the bulk electrolyte and silicon surface, thereby preventing electrolyte decomposition while allowing lithium ion transport
2Quantity of substance
If high-voltage nickel-rich cathodes are used to increase energy density, then capacity is improved, but oxidative instability of conventional electrolytes occurs leading to accelerated decay
Solution Approach 1:
The patent applies preliminary action by pre-forming a stable cathode electrolyte interphase (CEI) layer on the nickel-rich cathode surface before actual battery cycling begins. This is achieved through electrolyte additives that react during initial cycles to create a protective interface layer that prevents subsequent electrolyte oxidation and maintains cathode structural integrity at high voltages
Solution Approach 2:
The patent uses electrolyte additives as intermediary substances that mediate between the nickel-rich cathode and the bulk electrolyte. These additives form interfacial layers that act as protective intermediaries, preventing direct contact between the bulk electrolyte and cathode surface, thereby preventing electrolyte oxidation while allowing lithium ion transport
3Quantity of substance
If conventional electrolytes are used with silicon anodes, then initial capacity is achieved, but continuous electrolyte decomposition occurs leading to irreversible capacity loss
Solution Approach 1:
The patent converts the harmful effect of electrolyte decomposition into a beneficial protective layer. By controlling the initial decomposition through electrolyte additives, a stable SEI layer is formed that prevents further decomposition. The harmful decomposition reaction is thus converted into a beneficial protective interface that improves long-term battery performance
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 ether-containing electrolyte additives stabilizes the SEI and CEI layers, reducing electrolyte reactions, preventing Si anode expansion, and minimizing transition metal ion dissolution, resulting in improved cycle life, thermal stability, and safety of Li-ion batteries, while maintaining high energy density and power density.
Implementation Method 1
an unstable solid electrolyte interphase (SEI) layer can develop on the surface of the cycled anodes
Implementation Method 2
the large volumetric expansion (>300%) during the Li alloying/dealloying processes
Implementation Method 3
the ideal additives should be oxidized preferentially to the solvent molecule in the bare electrolyte, resulting in a protective cathode electrolyte interphase (CEI) film formed on the surface of the NCM (or NCA)
Implementation Method 4
oxidative instability of the conventional non-aqueous electrolyte takes place at voltages beyond 4.5 V, which can lead to accelerated decay of cycling performance
Data Source
AI summary
Electrolytes and electrolyte additives for energy storage devices comprising an ether compound are disclosed. The energy storage device comprises a first electrode and a second electrode, wherein 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 selected from ether compounds.