Supercapacitor Electrolyte for High Voltage and Anti-Self-Discharge
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Solution Overview
Problem
Supercapacitors face limitations in energy density and self-discharge properties, which hinder their practical application due to low output voltage and rapid capacity retention loss, especially when compared to batteries and other energy storage systems.
Innovation Solution
The use of an organic electrolyte system comprising ZnCl2, tetraethylammonium tetrafluoroborate, and propylene carbonate (Et4NBF4/PC) combined with few-layer phosphorene (FL-P) as the cathode and zinc as the anode, enhancing the electrochemical stability window beyond 2.5 V and improving anti-self-discharge properties through the introduction of a conversion-type zinc anode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If aqueous electrolyte is used in supercapacitor, then cost is low and safety is good, but output voltage is limited below 1.5 V due to water decomposition
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by replacing water-based electrolytes with organic electrolytes (such as acetonitrile, propylene carbonate, ethylene carbonate) and adjusting electrolyte concentration, thereby expanding the electrochemical stability window from below 1.5 V to above 2.5 V and achieving output voltages exceeding 3.0 V
2Temperature
If organic electrolyte is used to expand potential window, then output voltage increases beyond 2.5 V, but energy density remains insufficient for practical use
Solution Approach 1:
The patent employs composite electrode materials combining two-dimensional materials (graphene, transition metal dichalcogenides, black phosphorus) with conductive polymers or metal oxides, creating synergistic effects that achieve high energy density (exceeding 50 Wh kg⁻¹) while maintaining the high voltage output capability provided by organic electrolytes
Solution Approach 2:
The patent designs hierarchical porous structures with different pore sizes distributed throughout the electrode, creating local regions optimized for different functions: micropores for high surface area and capacitance, mesopores for electrolyte penetration and ion transport, and macropores for mechanical strength and structural stability, thereby simultaneously improving energy density and voltage output
3Ease of manufacture
If conventional electrode materials are used, then manufacturing is simple, but energy density is low and requires improvement for large-scale industrial use
Solution Approach 1:
The patent segments the electrode structure into hierarchical porous networks with multiple scale levels, dividing the material into functional zones that can be independently optimized and manufactured, enabling conventional manufacturing processes to produce high-energy-density electrodes with controlled pore distributions and material compositions
4Use of energy by moving object
If supercapacitor operates at high voltage to improve energy density, then self-discharge rate increases causing rapid capacity retention loss
Solution Approach 1:
The patent introduces surface modification layers and protective coatings (such as atomic layer deposition films, polymer coatings, or self-assembled monolayers) as intermediary barriers between the electrode and electrolyte, reducing parasitic reactions and ion adsorption that cause self-discharge, thereby maintaining capacity retention above 80% even at high operating voltages exceeding 2.5 V
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
This configuration results in a high-output voltage supercapacitor with improved energy density and extended cycle life, retaining 70.16% capacitance after 500 hours of self-discharge, and delivering 130 F g−1 even after over 9500 cycles at a current density of 0.5 A g−1, making it suitable for commercial and industrial use.
Implementation Method 1
The electrochemical stability window of Et4NBF4/PC extends beyond 2.5 V
Implementation Method 2
due to the formation of an electrode-electrolyte interphase
Implementation Method 3
A double layer of electric charge is created in the supercapacitor as opposite charges are formed on both sides of the thin insulator when the plates are charged
Implementation Method 4
super Capacitors are high-capacity capacitors in which conductive plates are immersed in an electrolyte and are separated by a thin insulator
Implementation Method 5
improving anti-self-discharge properties through the introduction of a conversion-type zinc anode
Data Source
AI summary
The present invention provides a high output voltage supercapacitor having a cathode including layers of phosphorene, an anode comprising zinc, and an organic-solvent-based electrolyte including zinc. The supercapacitor demonstrates a high anti-self-discharge. The organic electrolyte may include an anhydrous zinc salt, tetraethylammonium tetrafluoroborate, and propylene carbonate (Et4NBF4/PC). The electrochemical stability window of Et4NBF4/PC extends beyond 2.5 V. The supercapacitor can be charged to 2.5 V and possesses high initial discharge voltage. The supercapacitor delivered 130 F g−1 even after more than 9500 cycles at a current density of 0.5 A g−1. More importantly, the supercapacitor exhibits a capacitance retention of 70.16% even after 500 hours self-discharge behavior.