Flow Battery Gas-Gap Segregation for Shunt Current Repression
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Solution Overview
Problem
Redox flow batteries experience significant energy loss due to shunt currents caused by conductive paths of electrolytes between unit cells, with existing solutions increasing circuit complexity or structural complexity without effectively reducing power loss.
Innovation Solution
The implementation of gas-gap devices between unit cells to segregate liquid flow streams, using insulating materials and fin structures to prevent conductive paths, allowing discrete droplet transfer without simultaneous connection between upper and lower flows, thereby cutting off shunt currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If protection circuits are applied to repress shunted currents, then shunt current repression is achieved, but circuit complexity increases and more energy is consumed
Solution Approach 1:
The harmful conductive path of electrolyte between unit cells is extracted and removed by introducing gas gaps at strategic positions. The gas gaps physically separate the electrolyte flows, taking out the shunt current pathway from the system without adding complex control circuits or active components.
Solution Approach 2:
Gas gaps are introduced as intermediary elements between the electrolyte flows of adjacent unit cells. These gas gaps act as insulating mediators that prevent direct electrical contact between electrolytes while still allowing thermal and mass transfer, thus repressing shunt currents without requiring complex electronic protection circuits.
2Loss of energy
If paths of working liquids are changed to reduce power loss, then power loss reduction is achieved, but structural complexity increases
Solution Approach 1:
The continuous electrolyte flow path between unit cells is segmented into discrete sections by introducing gas gaps at specific locations. This segmentation breaks the conductive path into isolated segments, preventing shunt currents while maintaining the overall flow structure without requiring complex structural modifications.
Solution Approach 2:
Gas gaps are selectively introduced only at critical positions where shunt currents occur (between diverging manifolds and branch channels, and between flow-stream channels and converging manifolds), while leaving other areas unchanged. This local application of gas gaps targets the specific problem areas without increasing overall structural complexity.
3Loss of energy
If gas gaps are introduced to segregate liquid flow streams, then shunt currents are repressed, but liquid flow continuity may be affected
Solution Approach 1:
The gas gaps are designed to allow continuous droplet transfer of electrolyte from one unit cell to the next, maintaining the useful action of electrolyte circulation. The droplet-by-droplet transfer through gas gaps ensures that the electrolyte flow never completely stops, preserving system productivity while preventing shunt currents.
Solution Approach 2:
The gas gaps utilize pneumatic principles where gas pressure and flow dynamics control the droplet transfer process. By managing the gas-liquid interface and using gas flow to propel electrolyte droplets across the gaps, the system maintains hydraulic continuity of electrolyte circulation while using gas to block electrical conduction.
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
Effectively reduces shunt currents by preventing electric or ionic conduction across gas gaps, ensuring efficient liquid supply to each unit cell while maintaining battery structure integrity and reducing energy loss.
Implementation Method 1
the liquid flow streams between any pair of unit cells are segregated with gas gaps, so that very few of electric or ionic conduct of working liquid might cross the segregated gas gaps
Implementation Method 2
working liquids is allowed to cross the gas-gap by discrete transferring with the shapes of droplets or bulky-drops
Data Source
AI summary
A flow battery apparatus is provided with shunted currents repressed. The apparatus has a positive electrode device, a negative electrode device and a plurality of gas-gap devices. Gas-gap devices are separately set between branching channels and inlet and outlet manifolds of positive and negative electrodes. Each of the branching channels separately has an inserting tube to be inserted into one of the gas-gap devices. The diameter of the inserted vessel of gas-gap devices is bigger than the diameter of the inserting tube connected to a corresponding one of the branching channels. Thus, working liquids transferred to the positive and negative electrodes are segregated with coordination of the gas-gap devices. Only air spaces and discrete liquid drops are left between separated parts of the working liquids. Thus, shunted currents are repressed by preventing conductive paths from being formed between the positive and negative electrodes.