High Voltage Electrolyte Aggregates for LCO Cathode Stability
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Solution Overview
Problem
High voltage rechargeable batteries, such as lithium metal batteries, face performance limitations due to reactivity between battery components and traditional electrolytes, leading to limited capacity utilization and structural instability at high voltages, particularly with cathode materials like lithium cobalt oxide (LCO), where only about half of the theoretical capacity can be utilized at 4.2 V.
Innovation Solution
Development of electrolytes comprising a lithium-containing active salt, an ether-based solvent, and a diluent, specifically lithium bis(fluorosulfonyl)imide (LiFSI) with DME and TTE, which form localized solvent-cation-anion aggregates, reducing free solvent molecules and enhancing stability and coulombic efficiency, allowing operation at voltages of 4.4 V or higher with improved capacity retention and cycling stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional electrolytes are used in high voltage batteries, then the battery can operate at high voltage, but the electrolyte reacts with battery components causing limited capacity utilization and structural instability
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using localized solvent-cation-anion aggregates with specific molar ratios (1:1.2 or 1:1 of active salt to ether-based solvent), which fundamentally alters the electrolyte's chemical stability and reactivity characteristics, enabling high voltage operation without degradation
Solution Approach 2:
The patent creates a composite electrolyte structure consisting of multiple components (lithium-containing active salt, ether-based solvent, and diluent) that work together synergistically. The localized aggregates form a composite structure where different molecular components interact to provide both high voltage stability and capacity retention
2Temperature
If traditional electrolytes are used in high voltage batteries, then the battery can operate at high voltage, but the cathode structure becomes unstable due to phase transitions and cobalt ion dissolution
Solution Approach 1:
The localized solvent-cation-anion aggregates act as an intermediary layer between the cathode and bulk electrolyte. This intermediate structure prevents direct harmful interactions between traditional electrolytes and the cathode, thereby preventing cobalt ion dissolution and phase transitions while still allowing high voltage operation
Solution Approach 2:
The patent modifies the chemical environment at the cathode interface by creating localized aggregates with specific stoichiometry (1:1.2 or 1:1 molar ratios), which changes the interfacial properties and prevents detrimental electrochemical reactions that cause cathode structural degradation
3Ease of manufacture
If conventional electrolytes are used, then the battery can be manufactured with standard components, but the coulombic efficiency is limited and capacity utilization is only about half of theoretical capacity
Solution Approach 1:
The patent changes the concentration parameters of the electrolyte by creating localized aggregates with specific molar ratios of active salt to solvent (1:1.2 or 1:1), which fundamentally improves the electrolyte's ability to facilitate lithium ion transport and enables utilization of nearly the full theoretical capacity of the cathode material
4Temperature
If traditional electrolytes are used at high voltage, then the battery can operate at high voltage, but the electrolyte degrades and causes cathode/electrolyte interface degradation
Solution Approach 1:
The localized solvent-cation-anion aggregates are formed in advance during electrolyte preparation, creating a pre-stabilized structure that is inherently resistant to high voltage degradation. This preliminary formation of stable aggregates prevents interface degradation during cycling, enabling long-term stability over 100 cycles or more at high voltages
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 proposed electrolytes enable high voltage battery systems to achieve coulombic efficiencies of 99% or higher, significantly improving capacity retention and cycling stability, surpassing conventional electrolytes, and maintaining stability over 100 cycles or more.
Implementation Method 1
form localized solvent-cation-anion aggregates, reducing free solvent molecules
Data Source
AI summary
Disclosed herein are embodiments of an electrolyte that is stable and efficient at high voltages. The electrolyte can be used in combination with certain cathodes that exhibit poor activity at such high voltages with other types of electrolytes and can further be used in combination with a variety of anodes. In some embodiments, the electrolyte can be used in battery systems comprising a lithium cobalt oxide cathode and lithium metal anodes, silicon anodes, silicon/graphite composite anodes, graphite anodes, and the like.