Lubricant-Impregnated Surfaces for Flow Battery Drag Reduction
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Solution Overview
Problem
Electrochemical energy storage devices, such as flow batteries, face significant pumping losses due to high viscosity, flow velocity, and narrow channel dimensions, leading to decreased electrochemical energy efficiency, particularly with non-Newtonian rheology of flow electrodes.
Innovation Solution
The implementation of liquid-lubricant impregnated surfaces with micro and/or nano-engineered features that reduce viscous drag and promote plug flow of electroactive phases, allowing for efficient flow without residue and potentially overcoming yield stress without additional forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high carbon black content is used in flow electrodes to improve electrical conductivity, then electrical conductivity is improved, but viscosity increases leading to higher pumping losses
Solution Approach 1:
The invention changes the physical parameters of the channel surfaces by introducing liquid-lubricant impregnation with specific viscosity ranges (10-1000 cSt) and controlled film thicknesses (1-100 nm). This parameter modification reduces the effective viscosity at the wall boundary, allowing high carbon black content electrodes to flow with reduced pumping losses while maintaining their electrical conductivity benefits
Solution Approach 2:
A liquid lubricant acts as an intermediary substance between the channel walls and the electroactive phase. This intermediary layer reduces direct friction and viscous drag, enabling the high-viscosity, high-conductivity electrode materials to flow efficiently through the cell without requiring excessive pumping energy
2Quantity of substance
If narrow channel dimensions are used to increase energy density, then energy density is improved, but viscous drag increases leading to higher pumping losses
Solution Approach 1:
The invention modifies the boundary conditions at the channel walls through liquid lubricant impregnation, changing the effective no-slip condition to a slip condition. This parameter change reduces viscous drag in narrow channels, allowing high energy density configurations to operate with acceptable pumping losses by reducing the wall shear stress that scales inversely with channel dimension
3Power
If high flow velocity is used to improve power output, then power output is improved, but pumping energy losses increase
Solution Approach 1:
The liquid lubricant serves as a mediator that decouples the relationship between flow velocity and pumping power. By reducing viscous drag at the boundaries, the system can achieve higher flow velocities for improved power output without the pumping energy losses that would normally increase quadratically with velocity
4Ease of manufacture
If conventional surfaces are used in flow batteries, then manufacturing is simple, but viscous drag causes significant pumping losses
Solution Approach 1:
The liquid lubricant is pre-impregnated into the channel surfaces during manufacturing or activation, creating a prepared surface condition before the electroactive phase is introduced. This preliminary action of lubricant impregnation reduces viscous drag from the outset, allowing conventional manufacturing methods to produce low-drag surfaces without complex post-processing
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 approach enhances electrochemical efficiency by reducing pumping energy losses and maintaining flow efficiency with high carbon black content electrodes, enabling flow batteries to operate effectively with higher carbon black loadings and extending the operating temperature range.
Implementation Method 1
a liquid lubricant impregnated within surface features of the electrochemical systems
Implementation Method 2
liquid-lubricant impregnated surfaces with micro and/or nano-engineered features that reduce viscous drag
Implementation Method 3
a plurality of solid features disposed thereon, the plurality of solid features defining a plurality of regions therebetween, and a liquid lubricant disposed in the plurality of regions, the plurality of solid features retaining the liquid lubricant in the plurality of regions during operation
Data Source
AI summary
In certain embodiments, the invention relates to an electrochemical device having a liquid lubricant impregnated surface. At least a portion of the interior surface of the electrochemical device includes a portion that includes a plurality of solid features disposed therein. The plurality of solid features define a plurality of regions therebetween. A lubricant is disposed in the plurality of regions which retain the liquid lubricant in the plurality of regions during operation of the device. An electroactive phase comes in contact with at least the portion of the interior surface. The liquid lubricant impregnated surface introduces a slip at the surface when the electroactive phase flows along the surface. The electroactive phase may be a yield stress fluid.