Redox Flow Battery Stack Drainage for Standby Self-Discharge
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Solution Overview
Problem
Conventional flow battery systems face challenges in reducing self-discharge during standby phases, especially in compact systems with constrained vertical spaces, where electrolyte drainage by gravity is not feasible, leading to energy loss and slow response times.
Innovation Solution
A compact redox flow battery system with independently controlled electrolyte feed and drainage pumps, utilizing three-way solenoid valves and level sensors to mechanically manage electrolyte circulation and drainage, allowing for efficient electrolyte management without relying on gravity, even in vertical environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If tanks are placed at a height enabling gravity-based emptying, then drainage is simplified, but vertical space requirement increases
Solution Approach 1:
The patent replaces the gravity-based mechanical drainage system with an active pump-based drainage system. The pump (designated as element 14) mechanically forces electrolyte drainage without requiring height differences, thereby substituting gravitational mechanics with mechanical pumping to resolve the contradiction between ease of drainage operation and vertical space requirements.
Solution Approach 2:
The patent introduces dynamically controllable drainage through the pump system that can be activated or deactivated as needed. The drainage operation transitions from a passive gravity-dependent static system to an active dynamically controllable system, allowing drainage to occur without fixed height requirements while maintaining operational flexibility.
2Productivity
If electrolytes are continuously circulated, then energy storage efficiency is maintained, but self-discharge increases during standby
Solution Approach 1:
The patent implements dynamic control of electrolyte circulation by introducing controllable valves (element 12) and pumps that can switch between circulation and drainage modes. During standby, the system dynamically transitions from continuous circulation to drainage and isolation mode, preventing self-discharge while maintaining the ability to quickly resume circulation when energy storage is needed.
Solution Approach 2:
The patent applies preliminary action by draining electrolytes from the stacks before standby periods begin. This preliminary drainage action removes the electrolyte source that would cause self-discharge, and the system is pre-configured with valves and pumps ready to quickly restore circulation when needed, thus preventing energy loss before it occurs.
3Loss of energy
If pumps and valves are added for controlled drainage, then self-discharge is reduced, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by designing the pump system to perform multiple functions: circulation during operation, drainage during standby, and isolation maintenance. The valves and pumps serve universal purposes across different operational modes, reducing the need for separate dedicated components for each function and thereby mitigating the increase in device complexity.
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 solution significantly reduces self-discharge and improves storage stability by effectively isolating residual electrolytes during standby phases, enhancing the battery's response time and energy retention, as demonstrated by a reduction in energy loss from 420 Ah to 234 Ah.
Implementation Method 1
a pump (15) for circulating the catholyte from the tank (10) to the electrochemical cell (30)
Implementation Method 2
a drainage pump (14) for draining the residual electrolyte from said feed circuit (13) and from said electrochemical cell (30) to said tank (10)
Implementation Method 3
said drainage pump (14) being controlled by a solenoid valve (12) directing the electrolyte either towards the feed circuit (13) or towards the drainage pump (14)
Implementation Method 4
The drainage pump is controlled by a level sensor in the feed circuit
Implementation Method 5
Energy is stored via a reversible electrochemical reaction within the electrochemical cells
Data Source
AI summary
A system includes one or more redox flow batteries and includes a stack of several electrochemical cells. The electrochemical cells include a cathode compartment and an anode compartment. The cathode compartment is in fluidic communication, via a feed circuit, with one or more tanks of electrolyte called catholyte. The anode compartment is in fluidic communication, via a feed circuit, with one or more tanks of electrolyte called anolyte. The feed circuit of the catholyte, respectively the anolyte, includes a pump for circulating the catholyte, respectively the anolyte, from the tank to the cathode, respectively the anode compartments. The system includes a catholyte drainage pump and an anolyte drainage pump, the catholyte, respectively. The anolyte drainage pump is controlled by a catholyte, respectively anolyte presence detector, in at least a part of the feed circuit of catholyte, respectively anolyte.