Solid State Energy Storage Device Using Carbon Electrodes
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Solution Overview
Problem
Current solid state electrochemical capacitors face limitations in capacitance, specific energy, durability, and cost due to the use of expensive metal oxides and liquid electrolytes, which also restrict their scalability and application in durable electronics.
Innovation Solution
A solid state energy storage device is developed using a non-conductive, permeable separator membrane with electrodes made of high surface area carbon materials and a solid electrolyte comprising dissociated salt ions and a mediator, where the electrolyte is formed by mixing an aprotic polar polymer with a salt and mediator, and the assembly is hot pressed to enhance capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If metal oxides (RuO2, IrO2, NiO, CoOx, MoO2, WO3) are used as electrode materials to achieve high pseudo-capacitance, then charge storage capacity increases to milliFarad per gram to Farad per gram, but the cost increases significantly due to expensive rare metals
Solution Approach 1:
The patent replaces expensive metal oxides (RuO2, IrO2, NiO, CoOx, MoO2, WO3) with inexpensive carbon-based materials (activated carbon, graphite, carbon nanotubes, graphene) that can achieve comparable or superior capacitance through electrostatic accumulation and surface reactions, eliminating dependence on rare and costly metals
Solution Approach 2:
The patent changes the fundamental operating mechanism from Faradaic reactions in metal oxides to electrostatic accumulation in carbon-based electrodes, utilizing the high surface area of carbon materials to create extensive electric double layers that provide high capacitance without requiring expensive metal compounds
2Ease of operation
If liquid electrolytes are used in electrochemical capacitors to enable charge transfer, then electrochemical reactions can proceed, but the device reliability decreases due to leakage and corrosion
Solution Approach 1:
The patent transitions the electrolyte from liquid phase to solid gel phase by incorporating a gelator substance that forms a three-dimensional network structure, trapping the electrolyte solution in gel form. This solid-like gel electrolyte eliminates leakage and corrosion issues while maintaining the ionic conductivity necessary for electrochemical reactions
Solution Approach 2:
The gelator acts as an intermediary substance that bridges the properties of liquid electrolytes (ionic conductivity) and solid materials (structural integrity, no leakage). The gelator forms a network that holds the electrolyte in place while allowing ion transport, thus mediating between the conflicting requirements of reaction capability and reliability
3Stability of the object's composition
If the metal oxide layer is crystallized to improve structural stability, then the material becomes more stable, but the pseudo-capacitance decreases because RuO2 in the middle of the layer becomes inaccessible for electron transfer
Solution Approach 1:
The patent utilizes the porous structure of carbon-based electrode materials to provide extensive surface area and accessible active sites throughout the electrode volume. The porous architecture allows electrolyte penetration and ion access to internal surfaces, ensuring that all material contributes to charge storage rather than becoming inaccessible through crystallization
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 results in a high capacitance, durable, and cost-effective energy storage device with improved specific power and energy density, eliminating the need for liquid electrolytes and enhancing the accessibility of mediator molecules for charge storage, leading to increased conductivity and power utilization.
Implementation Method 1
a solid electrolyte comprising dissociated salt ions and a mediator
Implementation Method 2
the separator membrane is non-conductive, permeable to the dissociated salt ions and impermeable to the mediator
Implementation Method 3
The high surface area per gram provided by activated carbon greatly increases the size of the electric double layer, thus increasing the capacitance of the electrolytic capacitor
Implementation Method 4
a mediator and a substantially solid solvent, wherein the separator membrane is non-conductive, permeable to the dissociated salt ions and impermeable to the mediator
Data Source
AI summary
A solid state energy storage device has two electrodes, a membrane separator and a solid electrolyte having a substantially solid solvent, a salt and a mediator. The energy storage device stores electric charge by both Faradaic and non-Faradaic systems. The energy storage device may include activated carbon mixed with the electrolyte and sonicated to provide connection between the activated carbon and the mediator. The energy storage device is hot pressed to increase conductivity. The two electrodes may be asymmetric in amount of reduced and oxidized species of mediator.