Aqueous Hybrid Electrolytes With SEI-Stabilized High Cell Voltage
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Solution Overview
Problem
Current battery chemistries face challenges with high flammability, toxicity, and limited electrochemical stability windows, particularly in non-aqueous electrolytes used for Li-ion and Na-ion batteries, which restrict their performance and safety.
Innovation Solution
Development of aqueous and hybrid electrolytes with specific metal salts and solvents that expand the electrochemical stability window to support cell voltages between 2-3 V, accommodating high metal salt concentrations and enabling the formation of a protective solid-electrolyte interphase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-aqueous electrolytes are used to achieve high cell voltages (>3.0 V), then the electrochemical stability is improved, but the flammability and toxicity increase
Solution Approach 1:
The patent changes the fundamental parameter of the electrolyte solvent from non-aqueous (organic) to aqueous (water-based). This parameter change fundamentally alters the safety profile while maintaining electrochemical stability through the formation of protective interphases. Water-based electrolytes eliminate flammability and reduce toxicity associated with traditional organic solvents like carbonates and fluorophosphates.
Solution Approach 2:
The patent converts the traditionally harmful aspect of water (its narrow electrochemical stability window of 1.23 V) into a benefit by utilizing controlled decomposition of water at electrode surfaces to form protective solid-electrolyte interphase layers. These interphases prevent further decomposition and enable stable operation at high cell voltages (>3.0 V), thus converting water's instability into a protective mechanism.
2Object-affected harmful factors
If aqueous electrolytes are used to reduce flammability and toxicity, then the safety is improved, but the electrochemical stability window becomes too narrow (1.23 V)
Solution Approach 1:
The patent introduces solid-electrolyte interphase (SEI) layers as intermediary protective barriers between the aqueous electrolyte and the electrode surfaces. These interphases form through controlled initial decomposition of water and electrolyte components, creating dense protective layers that prevent further decomposition reactions. This intermediary layer effectively expands the usable electrochemical stability window beyond the theoretical 1.23 V limit of pure water.
Solution Approach 2:
The patent employs preliminary action by performing controlled decomposition of the aqueous electrolyte during initial charging cycles to form protective solid-electrolyte interphase layers before the battery enters normal operation. This preliminary decomposition creates a stable interface that prevents subsequent unwanted reactions, enabling the battery to operate safely at high voltages (>3.0 V) that would otherwise cause water decomposition.
3Reliability
If traditional non-aqueous electrolytes are used for Li-ion batteries, then the electrochemical performance is improved, but the manufacturing costs increase due to moisture sensitivity
Solution Approach 1:
The patent inverts the traditional approach by using aqueous (water-based) electrolytes instead of non-aqueous electrolytes. This inversion eliminates the moisture sensitivity problem that plagues traditional Li-ion battery manufacturing. Since the electrolyte is water-based, standard atmospheric manufacturing conditions can be used, eliminating the need for expensive moisture exclusion facilities and specialized handling equipment.
4Reliability
If high concentrations of metal salts are used to increase ionic conductivity, then the electrical conductivity is improved, but the viscosity increases
Solution Approach 1:
The patent changes the solvent parameter from non-aqueous to aqueous, which fundamentally alters the relationship between salt concentration and viscosity. Water's unique properties allow for much higher metal salt concentrations (e.g., >10 m for LiTFSI) without the exponential viscosity increase seen in organic electrolytes. This parameter change enables high ionic conductivity while maintaining acceptable viscosity for battery operation.
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 enhance the stability and safety of battery systems, allowing for higher voltage operation and improved energy density while reducing toxicity and manufacturing costs.
Implementation Method 1
aqueous and hybrid aqueous electrolytes that comprise a metal salt
Implementation Method 2
the initial decomposition of solvents in trace amount and the concomitant deposition of these decomposition products which deactivate the catalytic sites of the electrode surfaces
Implementation Method 3
Rechargeable batteries that output high cell voltages (>3.0 V) utilize non-aqueous and aprotic solvents to dissolve conducting salts
Data Source
AI summary
The present invention is directed to aqueous and hybrid aqueous electrolytes that comprise a lithium salt. The present invention is also directed to methods of making the electrolytes and methods of using the electrolytes in batteries and other electrochemical technologies.