Multi-cell Supercapacitor with Graphene Electrodes and Internal Balancing
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Solution Overview
Problem
Current supercapacitors require external balancing circuits to achieve high voltage, leading to bulky and expensive energy storage devices due to low stand-off voltage of individual units, which limits their application in high-power and high-energy density applications.
Innovation Solution
A multi-cell multi-layer supercapacitor apparatus with graphene electrodes is designed using a parallel-series configuration, allowing internal balancing without external circuits, and featuring nano-carbon composite electrodes for high capacitance density and low leakage losses, enabling operation at voltages exceeding 3 volts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If series-connected EDLCs are used to increase operation voltage, then voltage is improved, but device complexity and size increase due to external balancing circuits
Solution Approach 1:
The patent merges multiple EDLC cells into a single integrated apparatus with shared electrodes and common electrolyte, eliminating the need for external balancing circuits. The cells are electrically connected in series through shared electrodes while sharing a common electrolyte reservoir, achieving both voltage multiplication and internal balancing.
Solution Approach 2:
The common electrolyte and shared electrodes serve multiple functions simultaneously: they provide ionic conduction for all cells, enable electrical connection between cells in series, and perform automatic balancing through shared ionic pathways. This multi-functionality eliminates separate balancing circuitry.
2Temperature
If series-connected EDLCs are used to increase operation voltage, then voltage is improved, but device size and cost increase
Solution Approach 1:
The patent implements a nested structure where multiple EDLC cells are stacked within a single housing, with each cell containing electrodes and electrolyte that are spatially arranged to maximize density. The shared components (electrolyte reservoir, housing, terminals) are nested to minimize overall volume.
Solution Approach 2:
By merging multiple cells into a single integrated apparatus with shared electrolyte and housing, the patent reduces the total volume compared to separate connected units. The common electrolyte reservoir serves all cells, eliminating redundant electrolyte volumes and external connection components.
3Device complexity
If individual supercapacitor units are used, then simplicity is maintained, but voltage is limited to low levels
Solution Approach 1:
The patent segments the electrolyte system into multiple compartments (first electrolyte reservoir, second electrolyte reservoir) that are in communication with different cells, allowing each cell to operate independently at low voltage while the series connection achieves high overall voltage. This segmentation enables voltage multiplication without compromising individual cell simplicity.
Solution Approach 2:
The patent transitions from a single-cell two-dimensional structure to a multi-cell three-dimensional stacked configuration. By arranging cells in series through shared electrodes and stacking them vertically, the apparatus achieves high voltage in the voltage dimension while maintaining compact footprint in planar dimensions.
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 provides a compact, cost-effective, high-voltage energy storage unit with internal balancing, achieving high energy and power densities suitable for applications like regenerative braking and micro-grid VAR systems, while eliminating the need for external balancing circuits and reducing the cost of stored energy.
Implementation Method 1
Supercapacitors, also known as electric double layer capacitors (EDLCs)
Implementation Method 2
The first cell is stacked on the second cell and interconnected in a manner in which the first pair of supercapacitors of the second cell and the first supercapacitor of the first cell have a common electrode
Data Source
AI summary
A supercapacitor apparatus within a sealed housing to provide a high-voltage EDLC energy storage unit includes cells stacked on one another, with each cell having a set of supercapacitors that are interconnected within the apparatus in a parallel-series configuration to provide an internally balanced energy storage unit that is capable of stand-off voltages of 10 volts or higher. The energy storage unit does not require balancing resistors or more complicated external balancing circuitry. The electrodes of the supercapacitors are comprised of carbon nanotubes and graphene nanoplatelets.