Aqueous Electrolyte SEI Formation for Wide Voltage Windows
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Solution Overview
Problem
Existing aqueous electrolyte solutions for supercapacitors have a narrow electrochemical stability window due to low decomposition voltage, leading to low energy density and safety issues, while high-concentration solutions face electrolyte consumption and low ionic conductivity, hindering power and rate performance.
Innovation Solution
A wide voltage window aqueous electrolyte solution is formed through a physical process using a long-chain compound with opposite charge functional groups and a soluble inorganic salt, forming a waterproof SEI film via electrostatic adsorption to inhibit water electrolysis and maintain ionic conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ultra-high concentration solutes are added to form SEI films, then the electrochemical stability window is improved, but the ionic conductivity deteriorates
Solution Approach 1:
The patent applies local quality by creating a dual-concentration electrolyte system where ultra-high concentration solutes are localized at the electrode interface to form stable SEI films, while the bulk solution maintains lower concentration to preserve ionic conductivity. This spatial differentiation allows the system to simultaneously achieve high electrochemical stability at the interface and high ionic conductivity in the bulk, resolving the contradiction between these two properties.
Solution Approach 2:
The electrolyte system is segmented into two functional zones: an interfacial layer with ultra-high solute concentration for SEI film formation and a bulk phase with lower concentration for ion transport. This segmentation allows each zone to optimize its local function without compromising the other, enabling both high electrochemical stability and high ionic conductivity.
2Stability of the object's composition
If ultra-high concentration salts are added to form SEI films, then the voltage window is improved, but electrolyte solution consumption occurs
Solution Approach 1:
The patent applies preliminary action by pre-forming stable SEI films using ultra-high concentration solutes during an initial conditioning phase. Once the SEI films are established, the system can operate at lower overall concentrations, preventing further electrolyte consumption while maintaining the widened voltage window. The SEI films act as protective barriers that prevent direct contact between water and electrodes, eliminating continuous electrolyte decomposition.
Solution Approach 2:
The ultra-high concentration solutes serve as a cushioning layer that forms protective SEI films before normal operation begins. These pre-formed films cushion against subsequent electrolyte decomposition, preventing direct water-electrode reactions that would consume electrolyte. The SEI films absorb the stress of voltage fluctuations and prevent harmful side reactions during device operation.
3Stability of the object's composition
If water content is reduced to form SEI films, then the electrochemical stability is improved, but the power performance deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the local concentration parameter of solutes. At the electrode interface, ultra-high concentration creates stable SEI films for electrochemical stability. In the bulk solution, lower concentration maintains high ionic conductivity for power performance. This parameter differentiation across spatial zones resolves the contradiction between stability and power.
Solution Approach 2:
The patent introduces an intermediary mechanism where ultra-high concentration solutes act as mediators that form SEI films to stabilize the electrochemical interface. These SEI films serve as intermediary layers between water and electrodes, preventing direct harmful interactions while allowing controlled ion transport. The mediators enable the system to achieve both electrochemical stability and acceptable power performance by facilitating selective ion transport through the interface layer.
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 solution achieves a broadened voltage window, high ionic conductivity, and improved rate and cycle life of electrochemical energy storage devices, ensuring safety and environmental friendliness.
Implementation Method 1
forming a waterproof SEI film via electrostatic adsorption to inhibit water electrolysis
Implementation Method 2
the electrolyte is a soluble inorganic salt of an alkali metal
Data Source
AI summary
The present invention discloses a wide voltage window aqueous electrolyte solution for forming an SEI film based on a physical process, including: an additive, an electrolyte and water, where the additive is a long-chain compound having both opposite charge functional groups and having opposite wettability; and the electrolyte is a soluble inorganic salt of an alkali metal. The present invention further provides a method for preparing the aqueous electrolyte solution described above and use of the aqueous electrolyte solution in an electrochemical energy storage device, and the electrochemical energy storage device includes a button supercapacitor, a button ionic capacitor or a pouch supercapacitor. According to the present invention, fan SEI layer is formed at an interface through a pure physical electrostatic adsorption process, a free water content at the interface is precisely reduced to inhibit water decomposition, thus maintaining relatively high ionic conductivity while widening a voltage window, effectively overcoming the problems of low conductivity of a traditional high-voltage aqueous electrolyte solution and consumption of the electrolyte solution for forming an SEI film based on a chemical process, and realizing the high capacity, long cycle life and excellent rate performance in aqueous energy storage devices.