Rollable Zinc Bromine Cell Architecture for Dendrite-Resistant Energy Density
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Solution Overview
Problem
Zinc bromine flow batteries face issues with low system energy density due to ancillary systems and complexity, leading to high resistance and zinc dendrite formation, which limits their practical energy density to less than 40 Watt-hour/kilogram.
Innovation Solution
A zinc bromine electrochemical cell design with a cylindrical, folded, or stacked mechanical architecture and an aqueous electrolyte solution of zinc bromide, incorporating additives for zinc dendrite suppression and bromine sequestration, along with a porous separator and graphite felt to increase cell surface area and prevent shorting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If zinc bromine flow battery uses high concentration of zinc bromide to increase energy density, then theoretical energy density exceeds 200 Watt-hour/kilogram, but battery resistance increases significantly
Solution Approach 1:
The battery is divided into multiple cells connected in series or parallel, with each cell containing a portion of the electrolyte. This segmentation allows the system to achieve high energy density through multiple smaller units while managing resistance at each individual cell level, preventing the resistance issues that would occur in a single high-concentration cell
Solution Approach 2:
The patent transitions from a traditional flow battery configuration to a gel-based quasi-solid state system, changing the physical dimension of the electrolyte from liquid to gel. This dimensional change allows high concentration zinc bromide to be contained in a gel matrix that prevents excessive resistance while maintaining high energy density
2Quantity of substance
If high amount of zinc plating is used to increase capacity, then battery capacity increases, but zinc dendrite formation increases causing separator puncturing and shorting
Solution Approach 1:
A protective coating or barrier layer is applied to the separator before operation to prevent zinc dendrites from puncturing it. This pre-established protective layer cushions against the harmful effects of dendrite growth, allowing high capacity operation without compromising separator integrity
Solution Approach 2:
An intermediary substance or layer is introduced between the zinc anode and the separator to mediate the interaction. This intermediary prevents direct contact between growing zinc dendrites and the separator, allowing high zinc plating amounts to be used without causing shorting
3Ease of operation
If zinc bromine flow battery uses traditional flow system with pumps and tanks, then electrolyte circulation is achieved, but system complexity and maintenance requirements increase
Solution Approach 1:
The gel-based electrolyte system is self-contained and does not require external pumps, tanks, or plumbing for circulation. The gel matrix itself enables ion transport without mechanical assistance, making the system self-sufficient and eliminating complex ancillary components that would require maintenance
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 enhances the energy density of zinc bromine batteries by reducing resistance and dendrite formation, allowing for a higher capacity and improved reliability, achieving up to 200 Watt-hour/kilogram theoretical energy density while maintaining safety and reducing self-discharge.
Implementation Method 1
an insulating porous separator
Implementation Method 2
cathode graphite felt
Implementation Method 3
aqueous electrolyte solution of zinc bromide
Implementation Method 4
zinc bromine electrochemical cell
Data Source
AI summary
A zinc bromine electrochemical cell comprises an anode-side subassembly, an insulating porous separator, and a cathode-side subassembly. The anode-side subassembly comprises an anode current collector, an anode sheet, and an anode insulating net. The cathode-side subassembly comprises a cathode insulating mesh, a cathode graphite felt, and a cathode current collector. The zinc bromine electrochemical cell is rollable, foldable, or stackable.