Polyacrylic Acid Hydrogel Electrolyte for Bendable Supercapacitors
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Solution Overview
Problem
Developing flexible energy storage devices with polymer electrolytes that offer ionic conductivity, temperature stability, and electrochemical stability while being cost-effective and low in production costs is challenging, as existing redox-mediated systems are expensive and have stability drawbacks.
Innovation Solution
A flexible energy storage device comprising a pair of electrodes separated by a redox-active polymer hydrogel electrolyte, which includes a polymer hydrogel, charge balancing anions, and redox-active transition metal cations such as vanadium, chromium, manganese, cobalt, or copper, with the polymer hydrogel being primarily polyacrylic acid and the redox-active transition metal cations being cobalt (II) ions, forming a uniform film to maintain energy storage capacity when bent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid electrolytes are used in supercapacitors, then high ionic conductivity is achieved, but safety issues arise due to flammability and leakage
Solution Approach 1:
The patent changes the physical state of the electrolyte from liquid to gel form by incorporating polyacrylic acid hydrogel, thereby maintaining ionic conductivity while eliminating flammability and leakage issues inherent in liquid electrolytes
Solution Approach 2:
The patent creates a composite electrolyte system combining polyacrylic acid hydrogel with redox-active transition metal cations, achieving both the safety benefits of solid polymers and the electrochemical performance of redox-mediated systems
2Quantity of substance
If redox-mediated systems are used to improve energy and power densities, then high capacitance is achieved, but production cost increases
Solution Approach 1:
The patent employs inexpensive transition metal cations (Fe2+, Mn2+, Co2+, Ni2+, Cu2+) that can be obtained from common salts, replacing expensive redox mediators while maintaining high energy and power densities through redox reactions
3Object-affected harmful factors
If polymer electrolytes are used to improve safety, then flammability is reduced, but ionic conductivity decreases
Solution Approach 1:
The patent modifies the polymer electrolyte by incorporating hydrogel structures and redox-active metal cations, changing its properties to achieve both safety and high ionic conductivity simultaneously
Solution Approach 2:
The redox-active transition metal cations act as intermediaries that facilitate ion transport through the polymer matrix, enhancing ionic conductivity while the polymer backbone maintains safety by preventing flammability
4Adaptability or versatility
If flexible energy storage devices are developed, then adaptability is improved, but structural stability deteriorates
Solution Approach 1:
The patent employs a hydrogel-based electrolyte that inherently possesses flexible, gel-like properties, allowing the device to be bent and flexed while maintaining structural integrity and electrochemical performance
Solution Approach 2:
The patent creates a composite structure combining the flexibility of hydrogel with the structural support of transition metal-doped polyacrylic acid, achieving both adaptability and stability
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 device retains greater than 75% of its unbent energy storage capacity when bent and achieves specific capacitance of 300 to 380 F/g and energy density of 17 to 25 Wh/kg, with enhanced ionic conductivity and mechanical flexibility, making it suitable for applications in flexible energy devices.
Implementation Method 1
redox-active transition metal cations are at least one selected from the group consisting of vanadium, chromium, manganese, cobalt, and copper
Implementation Method 2
polymer hydrogel electrolyte comprises a polymer hydrogel, charge balancing anions and redox-active transition metal cations
Data Source
AI summary
A flexible energy storage device with a redox-active polymer hydrogel electrolyte is provided. The flexible energy storage device can include a pair of electrodes separated by the redox-active polymer hydrogel electrolyte. The redox-active polymer hydrogel electrolyte can include a polymer hydrogel, charge balancing anions and redox-active transition metal cations at least one selected from the group consisting of vanadium, chromium, manganese, cobalt, and copper. The flexible energy storage device may retain greater than 75% of an unbent specific capacitance when bent at an angle of 10° to 170°.